Slendytubbies 2 is the sequel to Slendytubbies, an indie horror fan game by ZeoWorks that turns the children's characters from Teletubbies into monsters in dark multiplayer maps. The popup sound plays when a custard-collecting player is suddenly confronted by one of those creatures, a staple scare tactic the series became known for on YouTube gameplay channels. Clips and edits later lifted the sting on its own, and it spread as a generic short jumpscare for horror edits, memes and prank videos far beyond the game itself.