One of the most common house rules in the game of beer pong. It occurs when one team shoots and the ball goes into one of their own cups. This often occurs when it bounces back and the team doesn't block it from bouncing into their own cup, or when the shooter sucks.
"It's your shot, Dude"
Dude shoots at the other teams cups, and the ball bounces off the front cup and back into one of the cups in front of Dude and his partner.