When a wild tuna forced you to take your pants off while rubbing itself all over your body leaving you covered in fish slime.
by Moondoggie1983 October 7, 2018
An oily, malodorous substance found in the folds and cracks of one's butt. Typically found after a hasty wipe and/or following a rigorous workout routine. Similar to butt cheese or duck butter. Could also be a prime ingredient in the making of truffle butter.
Noun: I itched my butt and retrieved a healthy dollop of Rump Grease.
Verb: My girlfriend Rump Greased my driveshaft. I had to take an immediate shower. It itched for a week.
Verb: My girlfriend Rump Greased my driveshaft. I had to take an immediate shower. It itched for a week.
by Doc184 March 8, 2016