My mother had this contest with two other friends for years.
A kitchen implement was sent, gift wrapped, but with all the packaging and instructions removed.
The object of the contest was two fold:
1. The other person preferably would spend a great deal of time pondering the intended use of the implement, which would not be obvious.
2. Once the other person figured out what the implement was used for, they would find it terribly useful and use it all the time.
I found out about this when she was chuckling gleefully over a letter in March, from her friend. The implement was a piece of wood. It had a broad notch at one end and handle at the other. No spoon. It had a smaller notch in the side, open more towards the handle. It had a magnet on the side. And that's it. What is it used for?
Her friend had puzzled over it for more than a month and now used it nearly ever day......