You shouldn't block people with your carts in the supermarket.
Joe was in the supermarket looking for a can of corn in the aisle.
Joe wants to walk across the aisle to the canned goods.
Joe pulls his cart as far to the side as he can while looking for the canned goods.
Joe leaves his shopping cart in the middle of the aisle while he looks for the canned goods.
The other customers are able to move past Joe while he is searching.
The other customers aren't able to get around Joe's cart because he left it in the middle of the aisle.