Step 1: Get a level 2 store
Step 2: Buy 5 Small Metal Racks
Step 3: Position 2 with their backs towards a wall near a corner but not against it. It should look like a small space you can walk in and out of. Position another rack with it's back facing the inside of the trap, this will allow there to be just enough space for a customer to squeeze into.
Step 4: Block the exit. When the exit is blocked this causes customers to wander around the store and eventually falling into your trap.
Step 5: Once the customer walks inside your trap, close it off with the last metal rack.
Profit: You now have a customer mascot who is now stuck inside your store, begging to be let out, while customers walk in and marvel at your great prices. All while ignoring your new mascot's pleas for help.