1.an exclimation implying that you don't believe something you have been told. leterally meaning if what was said turned out to be in fact, true you would give your ass as payment.

2. an expression of frustration
1. Thomas "Yeah my ass Karen didn't have sex with him"

2. Brandon "You finish mowing the lawn?"
Jerry "Yeah my ass I did"
by mysteryman16 May 18, 2006
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