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 February 9, 2010
 Get the asstoomug.
Get the asstoomug. by Joe Kicks Your Ass June 28, 2006
 Get the asstoomug.
Get the asstoomug. 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 5, 2009
 Get the asstoomug.
Get the asstoomug. by pv123 July 20, 2008
 Get the Asstoomug.
Get the Asstoomug.