Sometimes man-boobs come from simply being overweight and out of shape, but sometimes it's called gynecomastia, which is a fairly common condition in adolescent boys. Often it disappears as puberty fades away, but sometimes it is a lifelong thing. Severity varies, as does your choice of how to deal with it. Both my brother and my fiance' have or had gynecomastia, and my brother chose to have plastic surgery as soon as he was old enough (the surgeons like to wait until you're solidly out of adolescence to make sure that it won't just go away on its own, as often happens). My fiance', on the other hand, isn't terribly bothered by it -- to him, it's no bigger a deal than my un-shapely legs are to me, part of being a normal person instead of a supermodel.

I actually debated with myself a bit about whether to send this post, because I don't want to be telling you that you've got some kind of "freak disease" when all you need is some exercise and some weight lifting, or when it'll go away on its own in a year or two. However, I know my brother was so relieved to find out that it was something beyond his control -- it had bothered him to the point that he was starvation-dieting and injuring himself lifting weights, without its having any effect. So all I'm saying is that there is such a thing, and it's something that you may want to research and discuss with your physician.

You can find more information about gynecomastia at http://www.gynecomastia.org.