Shopkeeper glitch

This one is based on luck, but even so, you can use it to gain many coins and items.

You will need
And yes, that's pretty much it.
 * A pet
 * A shop

The glitch
Take your pet into a shop. As usual, it'd start picking things up and dropping them, and this is what you can use to your advantage. If you move to the doorway and rest until your pet picks something up, you can walk out with your pet, who will, in turn, drop that thing. It doesn't matter if it falls in the doorway or close to it, the item will be yours. And if you did not want the item at all, you can just drop it inside the shop again, where the shopkeeper, (if he isn't mad at you) will offer you money for it. You can repeat this indefinitely.

It takes patience, but it helps when you have no money in your pocket or when a leprechaun is robbing you continually.