When you take a dump in the bathroom at Mcdonalds
Fred ate 5 McMuffins and then took a McPoop at Mcdonalds yesterday.
by TahoeBob May 31, 2008
McPoops are the shits you take right after eating McDonalds. One usually gets the McPoops after eating a McDonalds item that doesn't agree with you or after eatig healthy food for awhile and then going back to McDonalds.
I had the McPoops for a day after that BigMac.
by Phil B. April 30, 2006