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1.
An asstoo is a tattoo that someone gets on their rear end. It is much like a tramp stamp but on the ass.
"That girl just bent over and I saw her asstoo, it was a tattoo of a butt crack."
by hannahhairplane November 05, 2009
 
2.
An asstoo is when you get your ass or hips tatooed. Girls do this more then guys.
Did you see her butterfly asstoo its hot.
by Joe Kicks Your Ass June 27, 2006
 
3.
The tattoo that girls get above their ass crack.
"Did you that girls asstoo?"
"No"
"Man it said "bootylicious", unreal. She let me take a pic of it!
by pv123 October 13, 2007
 
4.
When you get drunk and get a tatoo on your ass.
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