What do you call a boomerang that don't come back?
A stick.

And there's only one knock-knock joke that's actually funny...

Knock knock.
Who's there?
Little Boy Blue.
Little Boy Bl... oh, no...
Micheal Jackson!

What's brown and sticky?
A stick.

What do you call a dog with no legs?
Don't matter what you call 'im, he ain't comin' over.