i'm going to talk about this despite the embarrassment and regret that will surely ensue.
i played this game before, way back when i was probably 11 or 12. people were doing it at camp one day, and i was making fun of them (shock, i know), because even then i knew that this wasn't too smart. someone of course talked shit to me, so i said, fuck it i'll do it. because clearly that was the smart reaction.
you stood with your back against the wall. you bent over at the waist and hyperventilated, held your breath, then stood up and someone would put the butt of their hands against the sides of your neck. within a few seconds, you would pass out and have a weird little hallucination. when you exhaled, the person would let go of your neck and you'd fall over. you'd come to within seconds.
being 12, i thought it was just cutting of the air supply, but being older, i can say that it was cutting off the blood supply at the arteries. which is even stupider, as that can result in brain damage much faster.
i remember that i had what felt like a long dream, and i came to slowly. everything was in slow motion, and i was on the ground, and i couldn't immediately remember why. it was actually kind of a pleasant feeling, but it wore off within 10 or 20 seconds.
i guess this is what kids do when they can't get their hands on booze and don't have guitarjon around to make jenkem.