Missouri McFlurry

The act of a woman (or man) defecating in a public restroom while giving a man oral sex.

Person 1: "Bro, you'll never guess what happened!"
Person 2: "No, probably not."
Person 1: "I just got a Missouri McFlurry from this old lot lizard in the Flying J bathroom as a trade for some meth I got from a truck driver."
Person 2: "You need help, dude."