Maximus was a race horse spirit that thought he wouldn't be able to race again, after the owner put an end to his racing career, and placed his horse down when it got an injured leg at the end of a victory lap while crossing the finish line. Maximus was put down, but the horse's spirit came to life to search for a body.
Just as Maximus was running around the city, the horse stopped and noticed the party in a middle of the park filled with dozens of people in costume that could be possessed. You were at the costume party with your girlfriend, as she was wearing a horse jockey's costume, and you were dressed in a horses costume so it would match as you were spending time with her. Just then, Maximus possessed you as you were busy chatting with some of the other guests who were at the costume party.