A person you encounter whom is so irritating, you develop an insatiable urge to smack them uncontrollably with both hands at a rapid pace.
Dude! You spilled my soda! Chill out You Smack Attack!
When the urge to smack someone, particularly in a bar or social setting, becomes overwhelming to the point of having to control it.
Variation: Snack Attack: late night drunken snacking. Unlike Smack Attack, Snack Attack is commonly uncontrollable.
I'm surprised I didn't get kicked out of the bar last night for almost smacking that guy in the mouth. The Smack Attack was in full force!