how to know if a man is virgin ???

Yes--there is a physical indicator that men have which allows other's to know if he's a virgin or not. It's not a pretty method of figuring it out, but it's the only way. At the end of the man's urethra--the head of the penls, if you will--there sits a small flap of skin. When a man is a virgin, the flap of skin will be more prominent, and somewhat of a reddish hue. When a man is not a virgin, the flap of skin retracts, and becomes more of a pinkish colour. Also, if a man is a virgin, he will react differently to certain colours. Red will aggravate him, and blue will calm him. In non-virgins, this does not apply.

Hmm..good question. I don't know..WHY DON'T YOU TRY ASKING HIM!

There really is no answer to this. There are no physical changes, certainly. It depends entirely on how one defines virginity, I think, especially in males.