An excuse used to clear your status from a stupid act that you performed.

It basically comes from the idea that all events have shirts, regardless of how great the event really was.
Guy 1: I can't believe you banged her...
Guy 2: Yeah, I just did it for the shirt
Gu1 1: What shirt?
Guy 2: You know, the 'I banged your mom last night' shirt...
by Wardrich December 13, 2006
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