The peter cuff is the fold of skin that covers the glans. The glans is the rounded tip of a man's penis. The peter cuff protects the glans from getting irritated by urine and from rubbing against clothes.
At a Jewish briss they remove the child's peter cuff.
the extreme hypersensitivity is just one of many consequences of not retracting your peter cuff often enough or for long enough.
I'm uncircumcised - I can roll the peter cuff back falcid without problem, erect with a bit of pain.
But the main problem is that I can't masterbate/ejaculate with it rolled back. I've tried masterbating with the peter cuff unrolled, stopping while near climax and rolling it down then trying to ejaculate as well, but the pain just stops me from finishing off.