In a bid to reach a younger, hipper audience, Jockey is launching a pair of Web sites built for viral appeal. At StopSquirming.com, users can watch videos of a man and woman acting out various uncomfortable underwear situations. They can also send friends a humorous reminder to get new underwear and upload their own video reenactments. A second site, JockeyUnderwars.com, is set for launch next month. There, visitors will be able to challenge each other, in an NCAA Tournament-style bracket, to top each other with videos of themselves dancing in their underwear.