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.
A sexual maneuver that simulates an insurgent kidnapping during climax.
When having sex doggy style, secretly slip a pillow case off a pillow. Then seconds before you blow you load, forcible enclose your partner's head inside the pillow case using both hands, and pulling the opening tight around their neck. Next pull their body up and towards your chest, arch your back, and finally, let your baby yogurt go, relax then fall asleep.
If this maneuver is executed during anal sex it is known as a "Rusty Insurgent"
Male Example: Yo I pulled off a "dirty insurgent" last night! Satin pillow cases work way better than the cotton ones.
Female Example: That guy I went home with from the pub pulled off a dirty insurgent on me last night. He's so dreamy!!!