Where’s Brainiac when you need him? The latest mystery on the Web is who created the ingenious parody of Budweiser’s cultishly popular ”Whassuuup” ads, the ones with layabout pals hailing each other while ”watching the game, having a Bud.” The online homage replaces the spot’s original cast with five animated Superfriends — Superman, Aquaman, Batman, Wonder Woman, and Robin, all unleashing the ”Whassuuup” greeting in the classic ’70s-’80s cartoon’s famously robotic style. The parody has spread widely via e-mail — even to folks at Cartoon Network, which airs Superfriends reruns. But so far the perps haven’t owned up, perhaps because of the potential violation of copyright laws. (Repeated attempts to reach the site’s administrators were unsuccessful.) Not to worry: Cartoon Network isn’t bothered by the rip-off. ”Everybody here loves it — it’s very much the sort of irreverent thing we like to do,” says network spokeswoman Laurie Goldberg. Far from suing, Goldberg says the company wants to interview the creators for a job. Sounds like a plot twist even Mr. Mxyzptlk couldn’t anticipate.