This is just like the suggestion to have a hotkey to do actions in a gif or png sequence format, but instead a hotkey to have your character show a different emotion!
How it would probably work would be a hotkey would just swap the PNGs used to a new set that's designated by the user to be that emotion. The original would be a sort of default emotion, and then the hot keys you create could correspond to any number of emotions you like. Essentially it'd be like swapping the avatar completely on the fly, but perhaps the character you choose that contains all those emotions would be preloaded so that the change could be instantaneous.
Just a thought! LMK what you think. Loving using HONK so far!