gut flush 

The sudden and often violent series of bowel movements that occur after one has eating something his or her digestive system disagrees with. Often painful, this explosion leaves the recipient weak and tired but with a huge feeling of relief.

Guy 1: What are you going to KFC for?

Guy 2: I've been blocked for weeks. I need a gut flush so bad right now.

gut flush by the dirty liberal April 24, 2010