The diarrhea which usually follows a weekend of drinking and poor eating. Often not painful, but rather extremely relieving and requiring of multiple flushes to fully dispose of.
Boss: "Late to work on a Monday again Phil?"
Me: "Sorry but I had a Monday mudslide and my girlfriend threatened to break up with me if didn't clean the bowl afterward."
Culver's drive thru girl: "Hi welcome to Culver's, would you like to try our flavor of the day Monday Mudslide?"
Me: "I already had one this morning so no thanks but I'll take a hot fudge sundae"