I thought of this while eating breakfast, and came up with
this site after a few seconds on google (there is probably a better local option).
For $219.00 you can get 1,000 12" X 17" brown paper bags with 1 color image or logo printed on it. I was thinking you could send in "saveourchiefs.com" as the logo, only send the image upside down so it can be read while people wear the bags on their heads. Then you can hand these out in the parking lot before a certain game or all games. If you don't want SOC on it, then something simple like "Fire Pioli" might be good.
I don't know if anybody would get behind this, but I think this would be pretty funny. It might have been brought up before, if so, sorry for Q.
edit: And as Mr. FAX brought up, maybe this would make a decent surprise. I'm not sure any sports team has had fans show up with uniform paper bags...