A Drinking Man Joke

Here is a joke that the Judge told me:

A man walks into a bar and throws down a $100 on the bar and offers it to the first person who can bang down 10 pints. The bar is quiet, no one takes him up on the offer. One guy gets up and instead of taking the challenge, walks straight out of the bar. Half an hour later the guy who walked out comes back and walks up to the man and says he will take on the challenge. The Man looks at him incredulously and asks: “But why now after you walked out?”. The guy responds “I went next door to make sure I could drink ten pints first, before I accepted your challenge.”

I was laughing, my mate was laughing.  I wonder if the wonderful Sarah Silverman would be laughing too?