heart hands failure
When two characters form a heart hands duo pose, but one responds with a different gesture, such as a thumbs up, a victory sign or even a middle finger instead.
Popularized by famous fighting game player Justin Wong when a Chun-Li cosplayer did the thumbs-up at his expense. Hilariously, the same cosplayer would later try the same gesture with Umehara Daigo, only for Daigo to do the thumbs-up in turn.