slap-tastic
When someone does something that is either so cool or so dumb that an uncontrollable urge arises and you smack them.
Evan: "Man, I'm going to throw this pudding at the principal."
Mitch: *Slaps Evan*
Joe: "Evan, that was slap-tastically dumb."
Mitch: *Slaps Evan*
Joe: "Evan, that was slap-tastically dumb."