thats incredibly unlikely that I would even get yelled at for anything of the sort. I would never get in an argument with someone over their keys.
I think what i’m gonna do from now on, is ask the person once if they want me to call them a cab. If they decline and insist they can drive, i have to run by the bouncers on the way to the lot anyway, i’ll just swing in and let them know so that by the time i get back with the persons car, someone is already on their ass.
that way, i don’t have to put anyone in a headlock, or stab them with a ballpoint pen :smash2:. although sometimes i would love to. 
EDIT - Also on the legality of my responsibility, thats good to know. but it would be karma at it’s finest if I handed someone their keys, and they killed my best friend on the way home…