Well ... I heard a joke once that always makes me laugh. It goes like this:
Two men are sitting at a bar, chatting idly as the bartender cleans his glasses. Suddenly one man proclaims, "I can jump out that window, do two backflips, and come right back in!"
His bar companion smirks and says "Naaw you can't you're lyin!"
"Bet me fifty bucks?"
"You're on!"
As the bartender watches, both men approach the window. They are on the fourth floor of the building. The man who issued the challenge steps up on the window sill, hesitates - and then jumps out!
After performing two perfect backflips, he lands perfectly back inside.
The other bar patron can't believe it, and stunned, he hands over 50$. The winner of the bet smiles and says "Hey - I will give you back your 50 if you can do it!"
Suddenly, the bartender pipes up and goes, "Don't do it. Superman is a mean drunk."