I recall reading some years ago about one of the greatest and most elaborate long-running gags ever brought off.
A woman had a sort of goofy thing for pink plastic flamingos, and managed to wind up with fourteen of the damned things in her front yard. One morning she counted, and a couple of them were missing. Next morning a few more were gone. As the days progressed, they all disappeared. This, she found, irritating and upsetting. Obviously someone was stealing them in the night.
But no! She started receiving post cards of the "Having a wonderful time, wish you were here" variety from various parts of the world: Central and South America, the Bahamas, islands in the Caribbean, even (as I recall) a few from Africa and Hawaii. This went on for several weeks.
Then, one morning, she stepped outside and there were a couple of her pink plastic flamingos standing on her front lawn—with little cardboard suitcases and wearing sunglasses. Within about a week, all fourteen had reappeared, all with suitcases and sunglasses.
She never did find out who did it or how they managed it.