My friend once told me that he played a prank on his dad by putting lamps in his glasses, and when his dad put them on his eyes turned yellow. Yeah. I really don't have an excuse.
On the other hand, another friend once looked in a mirror and saw another person standing next to him, noticed that person first, and momentarily believed that he was, in fact, that other person. We also managed to convince him that Shaun of the Dead was based on a true story from a nuclear accident in Columbia, and that the Irish Navy still used wooden boats. Metal.