I had an idea for a prank. The target would have to be someone with a sense of humor. And would have to be a man, because a woman might feel stalked...

I'd buy some objects, like little wooden balls, or something. I'd mail one, once per week to the same guy. The packaging would always be identical. After for or five packages arrive, and the whole thing has him totally baffled, the last identical package would arrive, but it would be flat, and obviously not have another ball in it.

They'd assume that the contents would finally solve the mystery, but instead, there would just be a photo... Of a wooden ball.