Slimy Butt is when you can definately feel some moisture collecting in the butt crack, more specifically concentrated around the anus. Slimy Butt is most often caused by a poor job of wiping the butt after a poop. Slimy Butt often leads to Itchy Anus if not attended to.
Johnny-Boy: Aaahhh man, i had such a bad case of slimy butt i had to go wipe myself clean.
Todd: Good work Johnny-Boy, do you feel any better?
Johnny-Boy: You bet! I can finally walk around without an odd sensation in my crack.