I'll be wearing my Red RBK authentic tonight (in addition to my Flames t-shirt, wristband, belt buckle, socks, cowboy hat, and, yes, boxer shorts) and hope that others wear red too.
The only ones I'd probably feel a twinge of sympathy for are those who wear green since that would imply color blindness (people with
Red-Green Color blindness can't discriminate between red and green as both colors would look the same to them). However, I'd still point out that the colors they're wearing aren't red, and would offer to take them down the the Fanattic to find something more suitable like a T-shirt. If the price was reasonable, I'd probably offer to pay for it myself (I have a soft spot for color blind people).
However, I have no sympathy whatsoever for those who wear stupid colors like yellow, blue or brown, etc. Wrong game (place?), buddy.