Sometimes the clad coating on a coin doesn't lay right, and a coin will come out with some copper toning. Usually it's just a little bit, I've never seen one like that, very cool, and it may be worth something. Are both sides copper colored ??
How did you clean it? Electrolysis can cause clad coins and nickels to take on a pinkish tint due to their copper content. If it's silver, cleaning copper and silver coins together can cause the same sort of discoloration.
In that case, it may have been struck on a defective clad or copper planchet.
Another possibility is that it's a post-mint alteration: someone electroplated it with copper.
And of course the scenario I described in my earlier post could also apply: I've received clad coins in change which had obviously been cleaned— and some that needed to be!
Interesting. I think you would know its composition for sure (copper v. clad) if you took the edge of the coin and rubbed it against something like concrete (or just scratch it somehow)...you could see the color of the exposed metal.