I remember people diving in Levis a very long time ago, because they couldn't afford wetsuits and wanted something to protect them from getting scratched and cut up or stung. I have never seen anybody wearing Levis *over* a wet suit, but I suppose you could do it for the same reason - to provide some really minimal but cheap protection for your wet suit, or maybe for the fashion statement. But as was pointed out near the top of the thread, wet cotton is just about the worst choice you can make for heat loss when you get out of the water, and I would expect them to provide just about zero thermal benefit in the water, too. Not to mention the drag.