Body language my friend.
if you believe it to be one of the 4 individuals you have met, a real quick way to find out is to just confront them. As you approach pay attention to stance, eyes, movement. No body wants to be wrong/ or caught.
So, ask craze party d/ chick, what she did last night, if she is doing it, i bet there will be a smile, or a tell of some kind.
i wouldnt come straight out and say it, but hint enough to let them know what you mean, and there you go.
Or you can just set claymores all over the car (hidden of course) and go to sleep... when you hear the massive explosion, or multiple explosions depending on other cars/ chain reaction, you can just roll over, pull up your blanket, and sleep even tighter knowing they will never bother you again :thumbup:
i'd look around other cars too, when i was a kid i used to do stupid shit ( who didnt) but almost identical to what you are describing, maybe just kids being stupid kids. if other cars are marked up/ i wouldnt feel as solo'd out
good luck, let me know if you need an eye in the sky