When you hide in your sister's closet and wait for her to start masturbating, then once shes about to cum you jump out and yell "My Cock!" and slap her across the face with your cock.
George: "Yo Jay, your sister so fine."
Jay: "Yea I know, I totally albertoaxed her face last night"
George: "Damn, dude, I woulda payed to see that"