wen engaging in sexual activity, just before the male ejaculates he yells tuna surprise, at which point a friend jumps out the wardrobe and slaps the female in the face with a fish
by scotty boyNo1 December 22, 2008
While performing oral sex on a woman, the giving parter spreads the labia and screams "SURPRISE!" into her vagina
by Jboydabs March 02, 2015
When a pervert or deviant abuses a large-mouthed fish for sexual gratification, filling it with a substance resembling mornay sauce. An act of grievous fish-abuse.
Did you see that freak out the back of the supermarket? He had his pants around his ankles giving that mackerel a tuna surprise!
by ferrimunt April 07, 2009