When a regular bitch-slap just isn't enough, a Ninja bitch-slap incorporates the ancient use of covert agents or mercenarys of feudal Japan specializing in unorthodox arts of war. The functions of the ninja included espionage, sabotage, infiltration, assassination, as well as open combat in certain situations. The underhanded tactics of the ninja were contrasted with the samurai, who were careful not to tarnish their reputable image.
A properly executed Ninja bitch-slap will probably land you a top spot on the bad ass list, right under Chuck Norris.
Scott: I wouldn't mess with Trevor if I were you, man.
I heard he Ninja bitch-slapped one guy so hard he left the country- completely disappeared...
Joey: That guy graduated dumbass,
he works at Taco Bell.
Scott: Oh, did he, Joey?