Yukijoe

In Persona 4, a character named Yukiko Amagi eventually joins your party. She is famous in the Joe community for Joe flat out rejecting her calling her his "classmate" when he got to her romance check, and also for her laughing fits. Nearly every time Yukiko had a laughing fit in the game, Joe eventually started laughing with her, leading to twitch chat calling him "Yukijoe", a portmanteau of Yukiko and Joe's name. This phenomenon is represented by the jphKiko emote.