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The act of physically holding your ass-cheeks with your hands and running for dear life, dignity and decency towards the nearest restroom. And why? Because you've really gotta go.
Jeremy: Man, you know, I had a hilarious time yesterday.

Frank: Why's that?

Jeremy: Because me and my girlfriend were at the mall and she had to do a Billy Run. Dammit that was funny!

Frank: HAH!
by THat one guy nobody knows June 14, 2010
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