Among Us, developed by InnerSloth and released in 2018, exploded in popularity in 2020 as streamers and friends played its social deduction matches online. In that culture, sus became shorthand for suspicious, used to accuse another player of secretly being the impostor. Sussy grew from that slang as a sillier, more playful version, spreading through TikTok edits, Twitch clips and YouTube memes where it was attached to awkward glances and guilty behaviour. It remains popular because the joke is instantly understood even by people who have never played the game.