This one time 2 of my friends were play fighting and one of them (who is trained in BJJ, Muay Thai, and more) trapped the other in a rear naked choke. Unfortunately, my friend who was the victim of the hold did not know what tapping out was, so he just stood there getting choked out for about 6 seconds, until i pulled the attacker off him. When i looked at the victims neck, it had turned apple red and his face was flushed.
Oh yeah, and when he had the hold on him, the victims tongue was sticking out and his eyes were rolled back in his head. He was NOT playing.

Whenever someone starts a story with 'This one time'. It always reminds me of american pie when she says,

"This one time at band camp"

Thats kinda funny, as long as the 'victim' was ok.

I just saw a study done on the results of applying chokes. I am not sure when this was done exactly but it was last year sometime. They did a brain wave test on people after they had been choked. they applied the choke for 2 seconds, 4 seconds and 8 seconds. The original hypothesis was that the brain would restore its function once the person was brought back around. They checked 1 minute after the choke, 15 minutes after the choke, 1 hour after the choke, 1 day and finally 2 days after the choke. The choke held for 4 seconds did have the same brain wave activity after 2 days!!! They did not say when the brain wave activity did come back, but noticed a decrease in brain activity for 2 days at least, but they didn't go any further. when you practice applying chokes, care is needed, but at least its in the name of learning. Screwing around and "playing with chokes" is dangerous and stupid. The professor who did the study is continuing the study more in depth, but it gives practioners something to think about.I know Dillman did some studies with a cariologist in reference to his pressure pointing. These techniques need to be fully understood as to what you can do to someone. Look how many police accidentally hurt someone when they perform the choke or the constraint wrong. Its not something to be played with, or toyed with. It can cause some serious harm. Look at 'punch drunk boxers' we don't need to add martial artist to that group.