The phrase comes from Budweiser's Whassup ads that first aired in 1999, where friends greet each other on the phone with the stretched call. The campaign became a huge pop culture catchphrase in the early 2000s, and the Scary Movie parody in 2000 pushed it even wider. Clips of the greeting kept circulating on forums, ringtones and later meme pages, where the spelling wazup became a common search variant. It survives because it is short, instantly understood, and works as both a greeting and a punchline.