Fist bump is actually already in the game, it's reserved for a special event that happens after you collect all chaos emeralds!
I already knew that, I was just wondering if it could be an unlockable song or maybe something like Stardust Speedway or What I'm Made Of :) Something for people who want a really high unlock bonus, it's okay if adding another song is a no. Or maybe something like Stardust Speedway. Also I encountered a glitch where sometimes when I get the spring powerup, it launches me downward, sometimes into a pit or a sign.