...give it one Crystallized Sulfer and it will give back to you one of several different types of Fireworks (i.e. Firework: Tropical Flash), that you can set off yourself.
Others I have gotten:
Big 'Sploder Fireworks
Firework: Sparkle Rain
Firework: Rodcet Fire-Burst
Firework: Nagafen Fire
Firework: Ice Dance
Firework: Ice Dance (seemingly, there are 2 diff kinds, as they would not stack... that or they have a stacking bug at the time of this post)