Rude Rash Share definition Flag That special kind of rash that develops when you've bumped uglies with some scallywag of sexual ill-repute. "Hey, what's that?"."Oh, it's just my rude rash" Rude Rash by Chris Royle June 10, 2010 0 0 Get merch Get the Rude Rash mug. Buy Now — $32.95 See more merch