The phrase comes from Budweiser's Whassup campaign, first shown on television in 1999, in which a group of friends greet each other on the phone with a long, drawn-out Whassup. The advert became a cultural catchphrase, was widely parodied in films, television and other adverts, and stayed in popular memory long after the campaign ended. As short video and meme culture grew, the greeting was clipped, stretched and reused online, where its familiar sound still works as an instant, funny hello.