My local Wally World has a old-style bike rack, which is not bolted down. It usually gets shoved back behind the extra carts outside. For a while, I would drag it up to where I thought it should be, lock my bike to it, and head inside. They never would let me take my backpack in, even though it is smaller than some of the purses ladies were carrying in.

So one day, I ride right up to the door, dismount, walk up to the greeter/security person, and inform them that, since I cannot take my pack in, and that they posses a poor excuse for a bike rack, they will watch both my pack & my bike. Worked like a charm, I don't carry a lock to WalMart any more!