a machine with a metal pipe connecting your wee-wee tip to your rectum. So when the operator of the machine ejaculates, all the semen funnels into his asshole in the hope of making the operator pregnant.
Rick: "Did you know Steve had a baby even though he's a man?"
Nick: "Yeah I heard he used a nut-butt contraption to make that happen."
Rick: "Damn, well how about that."
The Butt Nut Fart is an action preformed by 3 people. One must be the butt slapper, another is to be the nut puncher, and the last is to be the one getting hit. The 2 hitter must hit the person at the same time which in turn will cause a fart.
Tom: Hey, what are you guys doing?
Chris: You’ll see Jeremy and Chris: BUTT NUTFART *Smack* *punch*
Tom: *Farts*
Guys riding 2-up on a motorcycle; or more generally, riding any 2-person device where one individual sits directly behind the other (second person being a male).
I wanted a ride on his motorcycle, but was uncomfortable going nut to butt.