This sound comes from Beavis and Butt-Head, the animated television series created by Mike Judge that first became popular in the 1990s. The characters' laugh became one of the show's most recognizable audio bits and spread widely through reaction clips, GIF captions and meme edits online. It is still used because the laugh instantly signals immature humor, mockery or gleeful stupidity without needing extra context. Even short clips are enough for viewers to recognize the reference.