Megan goes to a Biology class to expect to learn about rabbit and hares which are both lagomorphs, the technical subclass of mammals both rabbits and hares belong to.
The teacher on the other hand, uses the word bun instead, which is an informal way to describe a small rabbit and says buns are the scientific term, whereas hares and rabbits (the correct names of the animals) are the informal names.
The teacher tells that the smaller the bun, the higher ranking it is. Here, Randall pushes the notion that kitten rabbits are often considered cuter than the adults to an extreme, but obviously this is not true in the animal kingdom.  It is interesting that he chooses to use the word "rank" to describe rabbits: rabbits live in large groups with no formal hierarchy, unlike wolves who have very definite leaders and social structure.
In the next panel, Ponytail states that "at this time of year, a lucky few may catch a glimpse of a king bun" - referring to rabbit kittens (the smallest and thus, in the comic, the highest-ranking, hence the term "king buns") being born in Spring (when the comic was released). The comic ends with Megan clarifying that she has the correct understanding of what a "bun" is (which is probably what the reader is thinking at the same time), to which Ponytail replies that "bun" is the scientific term. It is noteworthy that Megan quotes the true scientific term for rabbit-like mammals, "lagomorphs", but Ponytail corrects her by stating that "bun" is actually the scientific term, when in reality "bun" is the most contracted and informal name for a rabbit.
The title text is presumably referring to photographing a rabbit and, for example, posting it on social media - something which would typically be done today if someone sees a rabbit in the wild. If the poster had failed to photograph the rabbit before it ran away, they may typically post a message saying something like "I saw a really cute bunny today!" with an emoji depiction of a rabbit (probably 🐇 or 🐰).
The transcript is almost done, but the setting/image of each frame has to be added, and someone may want to fix my possible typos. This is my first contribute to explain xkcd! 18.104.22.168 10:51, 18 May 2016 (UTC)
- I added the explanations about the images. Thanks for contributing! Ladidootdoot (talk) 11:21, 18 May 2016 (UTC)
- I'm pretty sure that student #1 is megan, someone may wanna check that out22.214.171.124 01:44, 19 May 2016 (UTC)
I assumed this was about hair buns, am I incorrect? 126.96.36.199 11:10, 18 May 2016 (UTC)
- I also believed that 'bun' was also referring to hair buns/ponytails, thus giving a visual pun to the comic. It would also add another level of the 'heirarchy' pun as well. 188.8.131.52 14:08, 18 May 2016 (UTC)
I think it's "bun" short for "bunny", an informal term meaning a rabbit (especially a cute one such as the ones shown in the comic). 184.108.40.206 11:16, 18 May 2016 (UTC)
Wolves don't actually have as strong a hierarchical structure as commonly believed, and don't have so-called "alphas" running the pack. Wolf packs are primarily a family structure that centers around the parents, in a natural non-tyrannical way, with different wolves making decisions and leading the pack at various times depending on their particular skills. For more information on this, refer to writings by David Mech, wolf biologist, who first coined the terms "alpha" and "omega" for wolves, and has for years been trying to convince people that those original theories are incorrect. 220.127.116.11 (talk) (please sign your comments with ~~~~)
Of course, 'buns' are also a euphemism for butt, which might clarify a thing or two, or at least add a more amusing context. 18.104.22.168 (talk) (please sign your comments with ~~~~)
I also believe the comic makes more sense when taking that meaning (bun for buttocks/derrière...) into account. 22.214.171.124 12:53, 18 May 2016 (UTC)J
Except for the fact in the very first frame Ponytail uses it in the singular while using the pointer to draw attention to an image of an animal. Has *anyone* used 'bun' in its singular form to refer to buttocks? 'Bum', perhaps, but not 'bun'. Given the rest of the panel's contextual talk regarding the 'buns', that particular interpretation never entered my thoughts. I wonder if the interpretation regarding the derrière is seen more by those of a certain age, generation or geographic group, i.e: the way soda, cola, pop, 'soft drink' and Coke are regional and/or generational terms for a sugary carbonated drink product. 126.96.36.199 07:01, 27 November 2016 (UTC)
I know that this is absolutely just a personal gripe, but the website is called explain xkcd, not spell-out-everything-that-happens-in-xkcd.
In relevance, this seems to be satire of current-gen's obsession with (mis)spelling things that are cute incorrectly (see: smol, birb, doge) and the situation in the comic is a role-reversal, with the teacher being a (teen/tween/memer etc.) and the students are questioning the teacher's professionalism.
The point about 'rank' could of course be some fictional idea that a younger person could attach to a physical entity to make the world more fun and interesting or something idk.
I would add this theory, of course, but i have no idea what i'm even reading when i read this explanation and don't know where to add it. 188.8.131.52 12:00, 18 May 2016 (UTC)
- I absolutely agree I have slowly been editing different explanations to try to try to reflect this, but it is a very difficult and tedious process, if you can contribute do it. Lackadaisical (talk) 13:14, 18 May 2016 (UTC)
- In the fictional rabbit-world of "Watership Down", larger rabbits are usually superior. However the story is about an unusual group in which a small rabbit, Fiver, is the "king." There is a telling scene of mistaken identity near the end in which attackers are scared off. 184.108.40.206 (talk) (please sign your comments with ~~~~)
Hierarchy is misspelled. Unless it's a convoluted pun on heir - hare (almost homophones) ? blagae
- A new version of the comic has been uploaded by now, with the misspelling corrected. So the heir-hare pun was probably unintentional. (blagae) 14:58, 18 May 2016 (UTC)
As soon as I read it, I was thinking 'bun' as in 'buttocks', yet there is no mention of that in the explanation? 220.127.116.11 (talk) (please sign your comments with ~~~~)
- Added that in the explanation, but I'm not sure at all that this was intentional. When there are images of bunnies it is not necessarily something that would come into mind. --Kynde (talk) 14:13, 18 May 2016 (UTC)
Smaller "buns" being higher valued -- confirms to me the reference to (male) buttocks -- but what no one else seems to have noticed is that "mammalogy" is a short distance from the non-word "mammology" (cf. mammogram) would be the study of breasts, another viewable body part. So the presumed confusion could be confused with mammalogy / mammology.... Asimong (talk) 06:29, 20 May 2016 (UTC)
Most of the explanations posted thus far seem off-the-mark to me. Especially the ones involving butts, I mean, c'mon... The comment above about "role-reversal" gets close to the heart of the joke (if any), though I think more than anything this strip is just Randall indulging his love for depicting people in roles of presumed authority spouting absurdities. (And for tiny bunnies, of course.) TBH, though, this one mainly gives the impression of being based on a private joke or conversation, or just referencing some meme I haven't seen yet. 18.104.22.168 16:14, 18 May 2016 (UTC)
- I think it's an obscure reference. Buzzfeed has The 33 Most Important Bunny GIFs On The Internet, which might be related to the "important bun" from 1663. Maybe Ponytail teaches internet sociology, not biology, and she hasn't clarified that very well. .42 (talk) 16:27, 18 May 2016 (UTC)
I would say the entire "buttocks" link that is currently reflected in the description is a very poor fit. Clearly "this time of year" is referring to spring, when rabbits are most commonly seen darting around, and when rabbit kittens are most likely to be born/leave their nests. "The image of a king" clearly has nothing to do with Ponytail, as there is an image of a "king bun" on the screen. This is most definitely a reference to the treatment of images of monarchy. For example, in the UK it is illegal to deface images of the Queen. Fendletruck (talk) 16:49, 18 May 2016 (UTC)
- I concur. Delete any reference to explanation about buttocks, and only state that some may think of this, but given that there are images of bunnies this is probably more saying of the person who thinks of butts than of Randall... ;-) I will leave it up to others to do the deletion though. --Kynde (talk) 18:04, 18 May 2016 (UTC)
Wondering if there's any tie in to the ancient but not quite defunct alt.devilbunnies, which was about evils buns, their cuteness, and people under their evil sway. The teacher in this case would clearly qualify as a "symp" (bunny sympathizer). 22.214.171.124 17:28, 18 May 2016 (UTC)
Just to be clear, there are studies which show that cuteness in humans has certain evolutionary advantages for human babies and may affect how humans treat animals they perceive as cute. I was tempted to expound more upon this in the explanation but the explanation is no place for that. Cuteness in animals is both relative and a perception, it is subject to change from person to person based on past experiences and preferences, it is also affected by hormones and mood. It is not a defense mechanism, it does not protect against predators. I know the edit which first mentioned the fitness advantages of cuteness didn't state that it does protect against predators but in my original edit, where I first mentioned fitness, I was trying to include information relevant to the comic, not information which was absolutely correct. And even cuteness doesn't protect rabbits from human poaching as much as conservation does. In most places rabbits are pests and are dealt with just as rats and mice are now. But since I know that if I include information which is not one hundred percent absolutely correct in all situations it will eventually get edited, even if it makes the explanation clearer, I will not include this at the moment, to spare the exhaustive detail it will inevitably spawn.
In short, rabbits are delicious and things like to eat them, no matter how cute they may be. Lackadaisical (talk) 18:40, 18 May 2016 (UTC)
TIL: baby rabbits are called kittens. Jkshapiro (talk) 00:50, 19 May 2016 (UTC)
I think everyone has missed the big joke here: They aren't attending introductory mammalogy, they're attending introductory MOMmalogy. 126.96.36.199 12:04, 19 May 2016 (UTC)
- Please explain? Jkshapiro (talk) 12:39, 19 May 2016 (UTC)
- It's a mother getting excited about a cute thing and gushing about it. (And pestering her friends about it on social media.) Smaller buns 'rank' higher because their smallness makes them cuter in the eyes of the beholder (regardless of what the actual rabbits think about it). Meanwhile the students seem to have misread the course name. If it's not actually Introductory Mammalogy, what else would it be but Mommalogy? 188.8.131.52 00:04, 20 May 2016 (UTC)
- Thank you, I see what you mean. But I'm not convinced it's what Randall meant: his strips don't tend to be about parents, and if he wanted us to make that particular connection then I think he would have added much stronger signals. I mean, aside from the lecturer's hairstyle, which suggests they're female, what other evidence do you have that they're a mother? Or that social media is in any way related to this comic? Jkshapiro (talk) 03:20, 26 May 2016 (UTC)
seriously, are you people trolling? I'm 100% sure this comic is about buttocks! ;)--184.108.40.206 14:23, 19 May 2016 (UTC)
It feels like the comic is intentionally reversing several concepts rather than simply giving nonsense (higher rank is normally larger and level formality is reversed) 220.127.116.11 (talk) (please sign your comments with ~~~~)
I, too, immediately picked up an undertone about butts. "This time of year" being spring, ladies often start wearing skirts and shorts after mostly longer clothes in the winter (especially in Mass. where Randall lives), and the occasional "bun" sighting is in fact a recognized annual recurrence. I think it has a place in the explanation as at least a wink-and-nod double entendre. 18.104.22.168 17:09, 19 May 2016 (UTC)
This comic just doesn't make sense. Randall had some half-ideas, none of them worked, and he just drew it anyway. I thought I was missing the joke so I came here and nobody here has an explanation that is a) internally consistent and b) funny. -Foobarbecue (talk) 23:04, 19 May 2016 (UTC)
- Not all of his comics are done for humor, some are simply absurd. I think this is one of those ones which is simply absurd. Unfortunately within the first few days of a comic coming out it is unlikely that the explanation here will be complete or have any form of consistent tone or style. It will be debated and edited back and forth. Some will be over analyzed to the point that any humor or consistency will be strained out of them. It is better to wait a week or so for the buzz around a new comic to die down. In fact, I usually avoid the newest comics but, I happen to like rabbits. Lackadaisical (talk) 23:53, 19 May 2016 (UTC)
As discussed above (and as currently indicated in the discussion) wolves are not a good contrast to rabbit social behavior. Can we think of a better one? I know many bugs, like termites, ants, and bees are all hierarchical, but I think we should choose some sort of vertebrate at least. Some suggestions of my own; Lions, Lemurs, Horses, can anyone else think of anything? Or should we find a way to reword the sentence altogether? Lackadaisical (talk) 00:12, 20 May 2016 (UTC)
Question: has this got anything to do with the iOS game currently the free game of the week in the app store, King Rabbit? 22.214.171.124 09:18, 20 May 2016 (UTC)
"King Bun" sounds like a World War 2-era euphemism for a Kaiser roll. 126.96.36.199 (talk) (please sign your comments with ~~~~)
As for Slavic word for rabbit meaning "Little King". I'm Czech myself, so I looked around for the etymology; found something on Czech wikipedia (https://cs.wikipedia.org/wiki/Kr%C3%A1l%C3%ADk_dom%C3%A1c%C3%AD#Etymologie), posting translated for your consideration:
(King - "král"; Rabbit - "králík", "-ík" can be used as a diminutive suffix, for example with "kůň" - horse, "koník" - little horse)
What does a rabbit to do with a king? Nothing, actually, but the words are still related. As rabbits were not native animals in Bohemia, our ancestors didn't have a name for them. When first rabbits were brought to Bohemia from Germany 13th-14th century, we also got their German name "das Kaninchen", a corruption of the Latin word "cuniculus". Because of phonetic similarity, the word "Kaninchen" was mixed with "Königchen", the diminutive form of "der König" - king, and the Czech word "králík" was born. 188.8.131.52 (talk) (please sign your comments with ~~~~)
Czech and Russian are quite alike indeed. But in Russian there is no way a word for rabbit (кролик) be read as 'Little King', these aren't omonims either. For 'King' there's a word "Король" [kɐ.ˈro.lʲ] if you will use appropriate diminutive suffix, which is "-ёк" [ʲɵk] , you will end up with "Королёк" [kərɐˈlʲɵk] - 'kinglet' (a bird of Regulidae family) that is not a bunny, although it's really small too. Same as male horse - "Конь" [ˈkonʲ] belittles to word "Конёк" [kɐˈnʲɵk] and has a second meaning - 'roof skate'.
Well, one may combine russian word "Кроль" [kro.'lʲ] meaning either 'male rabbit' (depricated) or 'crawl' swimming style (modern), with diminutive "-ик" [ˈʲɪk] suffix and result will be "Кролик" [ˈkrolʲɪk] - 'Bunny' but in case of second meaning that's simply a pun.
So no, not in Russian, as source word was Polish "królik" which was formed same as Czech "králík". 184.108.40.206 (talk) (please sign your comments with ~~~~)
At the risk of adding to the noise, I assumed the joke was in the course name: confusing the study of "mammals" with the study of "memes". Everything being taught is a memetic concept (in the modern sense of the word, at least). It seems the path of least resistance in terms of making the smallest change to turn an understandable scene into an absurd one. Randall uses this format a lot (i.e: the entire scene & meaning being changed simply by changing one key word). He's very punny. 220.127.116.11 00:37, 26 May 2016 (UTC)
I'm new to this comment thing hold your horses.
I was seeing bun as used in an online sort of "omigod look at the bun" kind of usage. Honestly, visit tumblr for a few minutes, search the tag #bun, everyone uses bun for bunny, rabbit, hare, etc. The hierarchy I thought was to be based on cuteness level, as the smaller the bun, the more bun is respected in these online circles, or by anyone, really. 18.104.22.168 02:01, 29 May 2016 (UTC)
Behold, the cinnamon bun. Nyperold (talk) 23:14, 8 November 2017 (UTC)