stink injection 

When a person or animal passes gas when one's buttocks is in direct contact with the furniture where one is sitting so as to make the smell of the flatulence stay in the furniture after one leaves the scene. As a practical joke, this is sometimes followed by someone else sitting in the same spot moments later, only to push the foul smelling flatulence back out into the air where one can breathe.

Person #1: Why is James flailing his hands in front of his face?

Person #2: Because I just gave that couch a stink injection.

(high fives)

Person #1: Good one Bro!

stink injection by celesguy1 July 15, 2011