The act of purposely or accidentally grinding, grabbing ass, or groping in any way at a concert; mainly in the mosh where it is easy to get away with it
Person 1: Dude how was the concert last saturday?
Person 2: It was epic, l was grinding up against this really hot chick
Person 1: Sounds like you got some pretty awesome mosh tail
A dogs tail wagging in a circular motion, much like a moshing speed metal freak
Hey, check out out that Shi-Poo doing the mosh tail.