From the FaceBook event page:

Come one come all on Friday October 25th to a Halloween Bike Parade!
Critical Mass/ bike parades are typically on the last Friday of every month.
5pm meet up in Monroe Park near the fountain. The ride will leave at 6pm!
Costumes encouraged as long as they aren’t the racist/sexist variety or other oppressive costumes.

Bring music, signs, kids, etc. To celebrate bikes and Halloween!
The ride will be a group ride and we will try to stick together- its no race!