Good idea. Seeing as I'm here, I'll try thinking up one.
Name: Brio's growth formula
Effect: Doubles the size of your racer for a limited time. Crushes all karts smaller than yours.
Juiced Up: Triples the size of your racer for an even longer time. Crushes all karts smaller than yours.
If you see me posting, it's because I've been asked to. Which I guess would mean I'm taking requests.