There's a very drunk man in a bar. He's going on about how ihs wife always nags him for staying out late and especially for drinking too much. After a couple more drinks he throws up all over his shirt. He cries to the bartender "WHat am I gonna do? My wife's gonna have my head!"   
The bartender tells him to take a $20 bill out of his wallet and put it in a separate pocket from the rest of his money and tell his wife that someone else threw up on him and gave him $20 to clean his shirt. The drunk has a couple more drinks and goes home to his wife.
He walks in and gives her $40 and tells her about the man giving him $20 for his shirt. When she asks about the other $20, the drunk replies "He shit my pants, too."