A short, stalky creature of female origin whose social superiors invite to pre-parties solely for the purpose of remembering to call a cab at a desirable point and obtain transit. Upon doing so, she promptly screams something akin to "The cabs are coming! Finish your drinks and lets go!," thereby ruining the pre-party.
"Cab Trolls" are a necessarily evil as without them pre--parties would often become so epic that they'd continue all night, and even into the next day, without anyone ever seeing an actual bar or a member of the general public.
Dude 1: "Why do you still hang around with that bitch? Don't you remember that time we gang-banged her, rubbed salmonella in her eyes, threw her in the back of that rape van and left her to die?"
Dude 2: "Bro, she's really good about calling the cab and will make sure we get out of here before we gotta pay cover."
Dude 1: "Oh, so she's a cab troll?"
Dude 2: 'Yea."