Three men walk into a bar.
The barman tells them, “If you can sit in my basement for a day, I’ll give you free beer forever. “
The first man walks out after five minutes and says, “It’s impossible, you got a swarm of flies in there. “
So the second man tries his luck, but it can’t take more than an hour.
Finally, the third man goes down.
When he returns a day later, the others ask him how he did it.
He says, “Easy! I took a dump in one corner and sat in the other corner!”
This joke is included in the Black Book of Jokes. You can order it from here.