A fart smack is when you sneak up on an unsuspecting sleeping friend or foe, squat over their slumbering face (pants optional) and unleash a large, preferably disgusting odored fart. Swiftly after you must wake them up with an authoritative smack to there face. Thus waking them up to a big, startled gasp of ass gas.

To have an extremely ugly face.

When you dab too fast, fart, and smack yourself in the face simultaneously.