Ty sussy comes from online gaming slang rather than a single film or television scene, so its exact first upload is hard to pin down. Ty is shorthand for thank you, while sussy is a playful form of suspicious that spread through Among Us memes and livestream chat. Together the phrase works as a tongue-in-cheek thank-you to someone acting suspicious. Short clips like this travel well on soundboards because they are easy to recognise, easy to reuse, and fit the fast pace of gaming edits, reaction videos, and short-form memes.