kentucky red eye
A prank in which, like mooning, one drops his or her pants, spreads the cheeks lavishly, but also contracts the rectal muscles, as if trying to poop or fart, such that the inner red color of the hole is plainly visible.
Johnny returned from class and unlocked the dorm room door. Alan was ready on the other side of the door, displaying a full Kentucky red eye. Upon opening the door, Johnny was overwhelmed with disgust, and scarred for life.