The sound one makes after smelling something terrible. Usually during or leading up to sex. Comes from the sound one makes by simultaniously expelling all the air from ones lungs in order to rid the lungs and nasal passages of a wrectched smell, and saying "wow".
Example:

Female: "Hey, you wanna bang?"
Guy: "sure, just let me pull down your pants.....BUHWOW!"
by guhooo February 22, 2014
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