Peppermint is a circle-shaped red & white peppermint ball that exclusively only appears in Abobo's Big Adventure. Despite its name, it is technically a ball.
Origin
Along with the Unicorn, this ball is from Circus Charlie. Charlie the Clown balances on it in Stage 3.
In The Game
The Peppermint only appears in the "Luck Dragon Lunacy" minigame, it can be collected as a point.