brain smack

An act of cupping ones hand over their own butthole, and farting into the hand, to later trap the gassiest stench while simultaneously whipping your hand out with great efficiency and speed to carefully keep the horrendous stench in your hand, then placing the hand under a poor unsuspecting target’s nostril. The stench will instantly travel up the nostrils and the sensation will smack the brain. Hence the term brain smacker

He brain smacked me.
He grabbed his fart and brain smacked me.
Brain smack means to catch your fart in your pants then throw it in someone’s face