This is an interesting money bank, the Micro Bank optical illusion.
Put a coin in the slot at the top, and the coin slides down the silver funnel, which becomes impossibly narrow at the bottom. The coin then apppears in the little box – but now the coin has shrunk to about a quarter of its normal size. No regular bank would get away with shrinking your money by 75%!
However when you want to get your money back, there is a little slot at the back, and when you slide this open, your money appears. Luckily it is now back to its original size. Phew!
Available online from Grand Illusions for £9.99 (~$19.68).