If you work at a costume shop, you might very well be asked to wear a costume at work. Perhaps you might have a costume at home that you’d prefer to wear.
Wearing that costume to work might attract attention.
If part of that costume is a gas mask, wearing that mask to work might attract attention from local authorities.
If part of that costume is an inert grenade, wearing that grenade strapped to your chest while going to work might attract significant attention from local authorities.