On the topic of whether you can tell the difference when erect between cut and uncut - every guy's penis is different. Some have foreskin that covers the whole head even when erect, others have foreskin that peels back when the penis gets erect. And some have no foreskin at all. Personally, my foreskin covers most of the head when I'm erect, unless I pull it back.

CasperTG

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You know, Blackadder, for me socks are like sex. Tons of it about and I never seem to get any.

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https://imgur.com/a/80hiRdm