Short hesitation sounds like euhhh have become a staple editing shorthand online because everyone recognises that filler noise from everyday conversation. Clips built around a single drawn-out uh or euhhh circulate on soundboards and in meme edits as a universal reaction, needing no context, language or setup to be understood. Its popularity comes from timing rather than a specific source, and creators keep reusing it for brain-freeze moments, failed speeches and uncomfortable silences where a character, and the audience, have nothing sensible left to say.