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1.
Played with both boys and girls, when you are "it", to tag someone you come up behind them and give him/her a swift slap right on the bum cheek, or you can slap both cheeks, if it pleases you to do so.
Dood, we got a whole gang togther and went out in a field and played a nice, friendly game of ass tag!!
by ken-dawg November 24, 2004
 
2.
A game that usually middle school children play, its when you run up behind the opposite sex and slap their butt and thus they are now it.
Hey, man are you playing asstag today cuz' i was just it and passed it on to this chick i know.
by JBreddy November 18, 2010