My brother had a ferret he loved which died since I drew this strip. RIP.
Cueball built wings for his ferret and his friend asks why, indicating that it would be foolish to think that this would allow the ferret to fly. Cueball did, in fact, build these wings in hopes of allowing his ferret to fly, but dissembles in order to avoid losing face with his friend. Then the friend suggests they go play video games instead, while Cueball imagines the ferret actually flying. The fact that Cueball lies about his goal may be a commentary on abandoning dreams to avoid confronting societal expectations.
The title text refers to the fact that Randall's brother in real life had such a pet ferret. As shown by the original caption, Randall drew this comic while the ferret was still alive, but then it passed away in between his posting it on LiveJournal and reposting it with a title text on xkcd.com. He now wishes that it will rest in peace.
This is the second in a six-part series of comics whose parts were randomly published during the first several dozen strips. The series features Barrel Boy, a character that is different from what would quickly become the xkcd stick figure style. The full series can be found here. After Randall released the full The Boy and his Barrel story on the site, it became clear that the original comic 20: Ferret was also part of the series. The comics are listed in the order chosen by Randall: