Men and Stretch Marks

I used to think that stretch marks were primarily a female condition because of pregnancy and hormonal changes, but my husband has some minor marks, as well. Even though his weight has been mostly stable since we met many years ago, he has formed stretch marks around his underarms and buttocks. Interestingly, the one area that tends to accumulate weight, his stomach, appears free from these univited visitors.

Why would his otherwise unblemished buttocks develop stretch marks and his more fleshy stomach be devoid of them?

I'm a 27-year-old man with stretchmarks. I'm actually quite skinny now, but I was heavy growing up, particularly in grade school and junior high (did the whole fat camp thing three times). I actually weigh less now than I did in junior high, which is pretty amazing considering how much taller I am.

I have stretchmarks on much of my body, but they're most noticeable on my stomach and back, and it's ridiculously embarrasing. I remember as a kid not wanting to swim without a shirt because I was embarassed by how fat I was, and now I'm embarassed to swim without a shirt because I don't want people to see the stretch marks. Considering how much work I put into getting skinny, I'd like to be able to show it off by strutting around without a shirt every once in awhile.