An asstoo is a tattoo that someone gets on their rear end. It is much like a tramp stamp but on the ass.
by hannahhairplane November 05, 2009
by Joe Kicks Your Ass June 27, 2006
Hey Wes, you got to sit down for this. We got drunk at the rugby game and ended up getting asstoo's.
by ALexfromradford October 04, 2009
by pv123 October 13, 2007