He's the main character from the low-budget animated movie "Dinosaur Adventure" (by Dingo Pictures) — that super cute green baby dinosaur with the red snout and yellow belly. The "Yee" meme comes straight from that movie (the scene where Oro yells "Peek!" but it sounds like "Yee!"), and TIO is the little star of it all. In the meme world and the related crypto coins, he's often seen as the "best friend" or the heart of the story ($YEE and $TIO is part of the dino family alongside $PEEK, $CREE, etc.).