PORTLAND (AP) — A horde of people dressed in inflatable Tyrannosaurus rex dinosaur costumes are set to descend on Portland’s Monument Square.

A Facebook event set up by Alison Cyr and Valerie Sanborn calls for more than 100 people in T. rex costumes to arrive Saturday around 3 p.m. to dance around. Sanborn tells WGME-TV the idea for the event started when Sanborn bought her own costume for $50 online.

Cyr says she bought one for her brother, and later held a mock photo shoot at Portland City Hall featuring two people in T. rex costumes eloping.

The costumes can be purchased online for around $50.