Kind of cousin of the Dirty Sanchez. Here, while banging a girl from behind, stick a finger up her ass and get some poo on your fingertip. Then put a little on another finger on your other hand. Right when you cum, rub a finger under each of her eyes, giving the appearance of an athelete's eyeblack, and then yell "First Down" and make the hand motion a football ref makes for a first down.
Last night I was giving Meg some doggy action, and gave her a Dirty First Down. She loved it.