I don't know of New World is an international supermarket, this matters as Little Shop was their promotion. Items are available on trademe.co.nz if you don't have the peanut butter. Shipping would probably be cheap.
Step 1: Gather These Tools and Materials
New World Little Shop peanut butter collectable, knife.
Step 2: Leverage
Lever the top off the peanut butter jar with the knife.
Step 3: Stash Your Stuff
The lid should come off and on easily. The space inside is relatively small, but large enough to hide a lot of things.