If a shop has diggable walls, it is possible to rob it by the following procedure:

- Destroy walls, including at least a corner wall and the two adjacent wall squares.
- Go inside shop, place items in corner whose adjacent walls have been destroyed.
- Go outside shop, place yourself in the place of one of the adjacent walls (technically "outside the shop", it seems).
- Kick items in corner into the place of the other adjacent wall.
- Now items are outside the shop but the shopkeeper won't do anything. You can take them and resell them to him.