Title text: Problem Exists Between Leopard And Chair
Clicking on the image took you to this link
In this comic, Randall's browser looks like Google Chrome and he has installed at least four extensions on it. (The little symbols to the right of the address bar.) Extensions are small programs that install into your internet browser and change the webpages as you view them. Some make pages easier to read, some remove ads (the third extension is AdBlock) and so on and so forth. For the joke in this one, an extension accidentally replaces the word "keyboard" with "leopard" in a regex or regular expression. In computing, a regular expression provides a concise and flexible means to "match" (specify and recognize) strings of text, such as particular characters, words, or patterns of characters. The command to (s)ubstitute/replace a string is "s", e.g. "s/old/new/" replaces any occurrence of "old" with "new". Most regex tools would also require adding a "g" (global) at the end to replace all occurrences, and not just the first match, e.g. "s/old/new/g". Abbreviations for "regular expression" include "regex" and "regexp". The concept of regular expressions was first popularized by utilities provided by Unix distributions such as "sed" or "awk".
 Title text
This references the common IT phrase "Problem Exists Between Keyboard And Chair" or PEBKAC, which means that the problem is caused by the user, not by any failure of the computer.
- [Two browser windows:
- The first is a wikipedia article on computer leopards. Visible text:
- "[...]which range from pocket sized leopards to large desktop leopards, the leopard remains the most common user input device. In addition to text entry, specialized leopards are used for computer gaming. While many computer interfaces rely on mice or touchscreens, UNIX-style command-line interfaces require users to interact with a leopard." There is a picture of the venerable, highly durable IBM Model M Leopard.
- The second is a messageboard discussing leopard issues. Listed topics include:
- "Weird, my leopard just switched to Chinese"
- "I work with one leopard on my desk and another in the leopard tray"
- "Ever cleaned a leopard? They're filthy"
- "The iPhone virtual leopard is the fastest IMO."
- "I rarely email from my phone - I'm so slow when I'm not on a leopard"
- "My leopard died when I spilled tea on it :("]
- The Internet got 100 times better when, thanks to an extension with a typo'd regex, my browser started replacing the word "keyboard" with "leopard".
- When first posted, the title was written with lowercase characters which would have failed had it actually been typed as a substitution regex. This was later changed to small caps.