A slash inflicted from the side of the mouth to the ear, the place a telephone or cell phone is placed, hence the name.
Hood Ninja: "Aye dog, yo I straight got ripped an once of them buds son." (This gentlemen was shorted one ounce of marijuana)
Drug Dealer: "Umm... no?"
Hood Ninja: (Pulls out knife, slashes drug dealers left side of the face, from mouth to ear) "Yo, screw me again bitch, and I'll make the right side match."
Drug Dealer: "Not ANOTHER telephone scar!!!"