Sitting down and taking a dump only to realize your out of toilet paper. So you have to get up and grab some with your pants down.
"I sat down and shit before I realized there was no toilet paper, so I had to get up with a Dirty Moon and use paper from the towel dispenser."
by coletolli August 30, 2012
When you moon someone and take a dump at the same time
Dude- you might want to turn on the wipers, that guy in the car in front of us just gave us a dirty moon.
by wskiter November 12, 2009