10 second rule by the Gracies
Sometimes you don't know how long to choke your best friend horsing around...and they die.
http://youtu.be/QrsBlDDA0Lg
I use it, I know many others here do too, perhaps without detailed instruction.
'Sleepers' have been around a long time, if you can use them standing in a fight, wait for the legs to go limp to know its on.
A Systema instructor I know, uses a common trouser belt on beginners standing up to show self-defense with a commonly carried article of clothing, the speed of the choke out, eye opener.
CPR awareness of simple actions.