See the previous parts.
I remember, when I was at school, my friends played with compression asphyxia. The “victim” (the one who’s supposed to experience euphoria) had to quickly breath in and out about 30 times (like a dog), then four or five other guys would press as hard as possible on the victim’s chest thus preventing him from taking a breath. No, not for long, something about 30 seconds. After that the “victim” behave like as he was drunk.
I could not expect that such kind of asphyxiation would become so popular in the contemporary schools (see the Russian newspaper article on the subject). The difference is, instead of pressing on the chest, they simply strangle each other with hands, scarves, belts or pillows. To experience hallucinations they play much harder. Many die…
In other words, do not try that at home. Use your imagination and enjoy manga (despite what the legal says, it’s much safer).