mud butt

noun2

1. •
   (slang, vulgar) An uncomfortable physical sensation or the actual staining of the buttocks and underwear caused by diarrhea, excessive sweating, or inadequate cleanup.

   • I've had enough legend. Legend gives me mudbutt, if you want to know the truth. — 2005
2. •
   (slang, offensive) Someone suffering from diarrhea, or a person who is messy and unhygienic in their personal hygiene.