You know, when I caught it, I thought it looked like a photoshop job, too. Except I was HOLDING IT! I also thought it looked like a taxidermist mounted a bluegill and painted it like a rainbow. But, believe it, it's real.
This is the second one like this I caught. The other one had a clipped fin and was a little bigger. This one had all its fins intact (that's how I know it was a different one).
This was on Donegal creek. I catch plenty of nice-looking browns that either were born there, are long-time holdovers, or maybe were stocked as fingerlings. I thought they had stopped stocking it, but there seems to be a new infestation of rainbows this year. Oh well, certainly decreased the time between hooking fish.