Interesting you mention it, because I've seen similar thing in JAV where they hold the Japanese whore's mouth open with something that is obvioulsy a dental implement. It's kind of like a horse's bit, but it actually holds the whore's mouth open, it doesn't just prevent the mouth from closing. I guess I don't have to suggest it now LOL!. Let me see if I can dig up a jpeg.
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"All my years in p*rn didn't quite prepare me for childbirth. I mistakenly thought all the stretching I did would make this easier."