Doonesbury: week of 7/12/2004 (Warning - may contain strong language)

This one?

Dunno. But I took it to mean jackass.

Jehosaphat?

Well, in one of the best known “Dirty Ernie” jokes, the R-word is “rat.”

"A big fing rat with a pk this long!"

Could also be a joking reference to the South Park film trailer (not the actual film):

Mr Mackey: Young man, did you just say the Q-word?

I knew it was a joke, but I am enjoying the “J-word” suggestions.

This is probably right, as he was in a class of gifted students. (Krelboynes? Crelboynes?)