A particulary unpleasant fart that is completely unexpected by the party being surprised; usually in a setting that is not fart-friendly.
Sitting in church with my friend, I released a silent fart that packed a horrendous odor. I wispered to him that he had been muffin surprised. He was outraged and relocated to another pew.
by K.O.T.W. April 19, 2010
When you go to perform fellatio on someone and there is a particularly surprising amount of pubic hair.
Sarah met a guy on Friday night with no hair on his arms or legs, but when she went to give him a blowjob he had a Surprise Muffin.
by Yep_checks-out August 6, 2018