Parties require a certain number of fans before a party is available.

This table shows the number of fans needed to unlock a party location, and how many are needed for the other stages of the party.

Party Open Stage 2 Stage 3 Collection
Burning Bernie 10,000 500,000 1 million With burning desire
Flaming Wheels 400,000 800,000 1.6 million Giant Rocket
Whiplash 1.2 million 2.4 million 4.8 million Lord / Lady

Defeating the boss at the end of a party will give you an item. These items are part of the collections that are listed above.