Nate Westheimer, a New York entrepreneur best known for holding a Silicon Alley popularity contest, attempted to persuade Valleywag to participate in an April Fools' joke. We said we'd cover it, so here's the story: Right about now, if Westheimer's prank goes as he told us, Mashable, CNET blog The Social, and Silicon Alley Insider should be attempting to persuade you of the existence of a new startup called Urlrurl.com. The website converts long Web addresses into shorter ones, as TinyURL does. Unlike TinyURL, its shorter URLs all redirect users to a YouTube page with a Rick Astley video, a silly stunt known as "rickrolling."