I kind of guessed it would be "unwrapped" while in the act as there's obviously a strong evolutionary advantage provided by the stimulation, but I've always pictured it more of a tight sheath that wouldn't stretch enough to open that wide. Why I would think that after watching two circumcisions is beyond me.
FWIW, my mother said my C was made so painful by the doctor that she would have never put another son through it. She's very much the tough love type so it's saying something that she was traumatized by the event enough to influence future decisions. It's probably good I was too young to remember it because I never gave second thought with my boys.
So I've been doing some independent reading because of this thread and I guess there are some different types of foreskins out there. I've been all TMI this whole thread but well, in my case I don't have a bunch of "extra" foreskin I guess. Saw some pics and I was kind of like WTF, that's not what's going on with me.