Haha, I don't know if something like that exists in the US. It's a shopping cart chip. Basically in most grocery shops in Europe you have to put a coin into the handle of a shopping cart in order to "borrow" it when shopping (which you get back after returning the cart to the cart stand). Since it's not always possible and not very convenient to have a specific coin whenever you're shopping, there are chips the size of the coin made by companies to use instead of a 1€ coin.