The sound comes from SpongeBob SquarePants, the long running Nickelodeon cartoon set around the Krusty Krab, where Diet Dr. Kelp is the show's fictional soda. A background fish customer losing his order became a reusable reaction because the complaint keeps escalating out of proportion. Fans clipped and shared it online alongside other customer gags like My leg! and it stayed popular as a shorthand for being dramatically left waiting for food or drink service.