The blblblbl sound has no confirmed single source and spreads online simply as an onomatopoeia for nonsense speech. Its name is the sound itself, typed the way a mouth babble looks in captions, which makes it easy to search and reuse on soundboards. Short clips like this became common in meme edits, reaction videos and chat soundboards where creators need an instant cue for rambling, teasing or a brain short circuiting. Because it carries no words or language, it works across audiences and remains a go to filler joke.