The word sus grew from online gaming slang for suspicious into a general meme accusation, helped by the popularity of Among Us and its impostor gameplay. Clips built around a drawn out really sus line spread on soundboards and in short edits because the phrase needs no setup and instantly frames someone as guilty. The Lenny face in the original title adds a smug, teasing tone, signalling the accusation is playful rather than serious, which is why the sound keeps circulating for jokes about lying, cheating and acting shady.