Rusty Ninja

After a sporting event; when your teammate is washing his hair and his eyes are closed, someone sneaks up behind him and checks his oil with their thumb (quickly slips a thumb in his ass), then runs off before he is able to rinse the soap away and identify the clandestine violator

After the game someone gave John a rusty ninja. John was attacked by a rusty ninja after the game. Be careful, there's a rusty ninja in there.

Rusty Ninja

The challenge of having to piss directly into all of your partner's available orifices (mouth, nostrils, asshole, and pussy if they have one) while you're both blindfolded

Person 1: "Did you just sneeze piss?"
Person 2: "Oh yeah I got rusty ninja'd"