Maybe one day you'll find out.
what is it?
If the idea turns you off, don't do it. If you can relax and use lots of lube and trust the guys (although you can also do it with female partners wearing strap-ons) it can send you over the moon. But you have to be willing. Don't let your guy force you into it, if you're in any way reluctant. Speaking personally, it's one of my favorite things
I really have no desire to find out.
No idea but it seems painful!