A game commonly misunderstood as a means of exciting euphoria. This can be dangerous, and if you're alone, you should'nt attempt it, coz it acn cause death, being misunderstood as a case of suicide. It is played by two method:
1. Strangulation (or increasing pressure on carotid artery and thus influencing baroceptors (mechanoreceptors or sensors) leading to vasodilation(widening of vessels) leading to insufficient blood supply to brain. Can lead to head trauma resulting in death if practised alone.)
2. Hypocapnia or low level of carbon dioxide in blood due to hyperventilation (a form of deep and rapid breathing.) This can causing alkalosis which causes vasoconstriction(or narrowing of vessels) leading to brain, resulting in neuromuscular irritibility and dizziness, misunderstood as euphoria(or exagerrated elation.) This leads to cerebral hypoxia(or less amount of oxygen) leading to unconsciousness.
This can be attempted as a fun game(in local schools) but the lack of oxygen, if not treated properly, can lead to death if left as such.
Never, ever try this one alone! Seriously. If something goes wrong there will be no one to help you. And I wouldn't condone trying hyperventilation as a means of achieving this effect. That one can really mess up the gas exchange in the lungs.
There are safe(r) ways of replicating this. I'm reasonably sure that strangulation is mostly involved with closing of the trechea (windpipe), rather than the carotid artery closure (the two arteries that run along each side of your throat), however, I have heard of that effect too.
There are plenty of people out there who enjoy these kinds of sensations. It's not really that weird if you think about it. I'm not one of them, but I've heard the rush can be quite exciting. If people are going to do these things, then I propose that you do so with at least one person (who is not partaking in the activity) around in case something goes wrong. In addition, stop before it gets to a point where they pass out. You can also manipulate things so that they won't actually get to the point of passing out, but will get light headed. Only block off some air/blood flow, but allow enough to keep them conscious (rather difficult to determine, but if this method fails, you can always stop before they become unconscious, like I mentioned earlier).
Sometimes the vagus nerve response also occurs, but that is unfrequent. Btw, strangultion has an impact on the windpipe as well as on the carotid artery(like Jubie mentioned.). So just try it out with a person who can give you aid withing a few seconds if you pass out, coz in some cases the patients die before a third party is contacted.
Don't ever do the choking game! My cousin died because of it, and it broke my heart, as we were very close! Never! Don't even try! Please, for the sake of your family and friends and the people who love you, don't even think about trying it!