This sound comes from SpongeBob SquarePants, the animated television series that first aired in 1999. The bubble transition became one of the show's most recognizable audio cues because it regularly marked scene changes and short time skips. Online, creators adopted it for meme edits, nostalgic cartoon compilations and lighthearted transitions that need an obvious but friendly cut. It remains popular because the sound is brief, instantly recognizable and strongly tied to the underwater style and pacing people associate with SpongeBob.