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1.
greeting to a friend of many years or special closeness. Reply is always You a nuddin'!
First guy-Cows Ass!
Second guy-You a nuddin'!
by Rahlow July 29, 2005
 
2.
phrase that is easily mistakeable for "How's that?"
Pete: so how is the weather?
You: Cow's ass?
by Shifty February 02, 2004