As a verb, it means to dump
a bunch of exposition at the end of a movie or TV show
that has radical consequences for the story (e.g., the exposition states
that the main character later died
tragically), especially if it would have been better to show
this development instead of describe it.
comes from episode 4F12 of the American animated series "The Simpsons" ("The Itchy & Scratchy & Poochie Show
the new addition to the animated show
"Itchy & Scratchy", Poochie
(voiced by Homer), proves extremely unpopular, the producers decide to kill him off. Homer tries to persuade them otherwise by reading a touching
speech as Poochie
that he thinks will end up in the show
and endear the viewers to him. Instead, in the final
cut, somebody else provides Poochie
's voice, and states
that the character has to return to his home planet. Crude animation then depicts Poochie
"beaming up", and a note is tacked on that reads, "Poochie died
on the way back
to his home planet."
Real-life example, from Fark.com (discussing the show
Farker: "NBC canned it before it could be given a proper funeral. They Poochied the ending."