Image text: Ever notice how the more successful observational comics become, the more their jokes focus on flying and hotels?

Alright, open mic night.  Everyone's favorite night.

In the first frame Cutie/MC Aphasia is not a very good rapper because Aphasia is a disorder that effects the part of the brain that controls the ability of speech.  So, as you can see in the comic, MC Aphasia has a very difficult time speaking let alone rapping.

In the second frame, Black Hat is reacting to a Yo Momma joke that someone in the audience possibly yelled his way and starts off a common "Yo Momma" joke - "When yo momma sits around the house, she really sits AROUND the house."  But instead he goes in another direction to something that is a bit more off the beaten path.

In the third frame Cueball/MC Quine is a computer science joke.  A Quine is a program that produces its source code as its output.  In other words, what MC Quine puts into the rap is exactly what he gets out of it.  Hence the repetition of the same line.  In this case, the source code of the rap is "Yo, I'm MC Quine and I'm here to say,".

And completing the xkcd trifecta is the last comic, is a Lord of the Rings joke.  I'll call him "Beret" and is riffing off a common observational comic routine in which the comic observes that men go to the bathroom alone and women go in groups.

The image text is a reference to how when comedians become more famous, they travel more to other cities to do their comedy.  In the case of observational comics, the more they travel, the more they have time to observe both hotels and flying and nothing else.

Image text: Someone should really bring them a ladder and remind them to build the Endless Stair *first* next time.

This is a Lord of the Rings reference and the character with the beard and hat is Gandalf.  The four shorter characters are the hobbits that were also members of the Fellowship of the Ring.  The comic is making a joke on the fact that if the dwarves dug too deeply, then they just were unable to get out.

Image text: Using a ring to bind someone you covet into your dark and twisted world? Wow, just got the subtext there. Also, the apparently eager Beyoncé would've made one badass Nazgȗl.

The song playing in this comic is "Single Ladies" by Beyonce.  Which apparently had one of the best videos of all time... Anyhow, Gil-Galad was the last high king of the Noldor in Middle Earth.  Galadriel was a queen of the elves in Middle Earth.  Eru was the one god of Middle-Earth who created the Elves and Men, and Aule created the Dwarves, but Eru eventually approved Aule's creations.  So, he sort of created the Dwarves as Eru was the only god to give a spirit to a being, as he did with the Dwarves.

The character in the beret is apparently the bartender in a bar that Sauron frequents.  In the comic, Sauron upon hearing the song by Beyonce in the bar, has the idea to create his magic ring plan which presents the plot of the Lord of the Rings triology of books and movies.