My dad was out in the shed and he found a pair of old sunglasses. They were Beatles-style, round-framed glasses with ruby red lenses. He was immediately attracted to them.
Dad decided to drive to the store wearing his new specs. After he passed through the intersection in the center of town, he began to suspect he had run a red light. There had been squealing brakes and cursing. What was confounding was that the light had clearly been green.
The quandry resolved when Dad looked at the lighted sign on the bank. It looked green in his glasses. Normally it was red.