Barnyard Tennis
The actual phrase that means two people ass to ass, passing an egg back and forth until one cannot return it. Loser typically is made out to eat the resulting egg
"I saw some dipshit playing Barnyard Tennis and calling it Farmyard Tennis. You could tell he's a city slicker, not only by what he called it, but also because he ate the shit covered shell with it when he lost, and didn't even hard-boil it first. Oh, and the nasty bastard was playing it with another dude."