Dogs Don't Tell Jokes — Louis Sachar

Why did the guy eat two dead skunks for breakfast?
Because live ones squeal when you stick the fork in.

Gary W. Boone knows he was born to be a stand-up comedian. It's the rest of the kids in his class who think he's just a goon. Then the Floyd Hicks Junior High School Talent Show is announced, and he starts practicing his routine nonstop to get it just right. Gary's sure this will be his big break -- he'll make everyone laugh and win the $100 prize. But when an outrageous surprise threatens to turn his debut into a disaster, it looks as if the biggest joke of all may be on Gary himself.