The full story:
The term originates from an episode in 1995, and was spoken neither by Homer
nor Bart, but by Groundskeeper Willy:
[2F32] 'Round Springfield'
Written by Joshua Sternin & Jeffrey Ventimilia (teleplay) and Al Jean & Mike
Reiss (story)
Production code: 2F32 Original airdate in N.A.: 30-Apr-95
A little later, Bart puts his hand up.
Bart: Mrs. Krabappel, I'm done failing the test. Can I _please_ go to the
nurse?
Edna: Gosh, Bart, maybe you really are in pain.
Well...it would be cruel not to let you go.
[files her nails, hums the national anthem]
[hums part of "Stars and Stripes Forever"]
Heh heh heh, _now_ you may go.
Bart: [walking into nurse's room] Lunch Lady Doris? Why are you here?
Doris: Budget cuts. They've even got Groundskeeper Willy teaching French.
Willy: "Bonjourrr", you cheese-eating surrender monkeys!