I can't remember what it's called. I would never do it because it doesn't do anything for me, and the risks are too high. That's how the actor David Carridine died. I thought it was more than suicide; he was into that, maybe trying it alone.

But some clients are idiots.

I've had a submissive sugar babe request choking.  It's really side pressure on the neck which impedes blood flow, rather than crushing the windpipe.   I am leery of that sort of thing because there are always risks.  
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Somewhat distinct from merely grasping the neck in a symbolic gesture of dominance.  Which is fun if you are into D/s play.
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But yeah, it all has to be with consent.  

My rule of thumb (or hand) is to do it lightly enough that they feel it but it doesn't leave a mark.

I was choked once by a provider. She just did it without discussion and took me by surprise. At first I was surprised by it and let her continue to do it as I thought that it might be a turn on for her and in the spur of the moment I kinda liked it. However afterwards, I did not care for it that much and the next day my throat and neck were sore for a few days. If it happens again I’ll most likely stop it.

Leave no marks if you do because I can guarantee it; if LE, the doctor, or you are in ER...they will investigate. Especially if it's a female with the marks, most of the time now, when you go into a hospital, they will go over your whole body for marks.