A handle usually directly above the door or passenger window in a car originally designed to hang dry cleaned clothes. Since no one does this anymore, the only known purpose is for holding on for dear life when riding with new or non-drivers, the elderly, off-duty prison guards or people in other traditionally suicide prone lines of work, and henchmen on a violent carchase. The handles are usually grabbed with a cry of, "Oh shit!"; thus the moniker.
"OK Gordy, turn left at the pharmacy here. Yes, this corner. Well, just turn at the next blo...Jesus, watch out for the curb! Oh shit, Nik, grab the Oh Shit Handles!