Stretch marks are caused by the skin stretching beyond its limits (thus the title). Because of this, it is severely damaged.
Stretch marks aren't just red lines, they are scars from your skin not being elastic enough to support the size.
7 months with cocoa better will make them invisible (so says many pregnent women). I doubt yours (males) are half as bad as a pregnent womens are... All the way up the stomach, lines. It's hideous.
Get your mom/female friend/girlfriend/sister to buy you some stretch mark "cream" for pregnent women who have gotten them. These ladies go into the store demanding it. I'd imagine you'd find something that works or they'd be obliterated by a stampede of angry moms wanting their "beauty back"
You'll hear "stretch marks will never go away". Is this true? Sort of. If the stretch mark is invisible, who gives a crap? We're not scientists, we're men, in the event that we care about the way that portion of our body looks (due to scars) we will make them go away visually, and be done with it...
Will they fade away? They'll go from red/purple to a color very similar to your skin tone... So in essence, they do.
Will a tan help? Yeah, of course.
Need a real quick solution? If you need to hide um or something, chicks use makeup to hide um. You can always do that I suppose.
Men sweat this out heavy sometimes, because they can be rather unattractive. Just find some creams and stuff, take care of it. Big deal? Nah, nothing you can't handle -- if you take the time and read up on it.