Another problem with marking people as stupid is the few smart ones would figure out what's going on and leave and the concentration of stupid people would become even higher.
Ok, here's an additional list of things to do that I found on the internet today. I removed the duplicates.
Move the displays into a maze, then stand at the end and congratulate anybody who makes it out.
Hold a box tightly. if people look at you, clutch the box to your chest and say, "Mine."
Hide inside the clothing racks, and when someone begins to look through the racks, stick your head out and say, "Do you mind?"
Stand in the freezer with a sign that says "Do not thaw until 3000 A.D."
Go to the checkout line and page yourself. Slip away, then come back 5 minutes later, saying you were paged. Repeat until you're told to leave.
Stick price stickers to yourself and lay on the conveyer belt. When asked what you're doing, say, "I got hungry and ate all my food."
Take shopping carts for the express purpose of filling them and stranding them at strategic locations.
Run up to an employee (preferably a male) while squeezing your legs together and practically yell at him "Where are your tampons?"
Try on bras over top of your clothes.
Make a trail of lemonade on the ground, leading to the restrooms.
While walking around the store, sing in your loudest voice possible "I smell sex and candy"
Walk up to an employee and tell him in an official tone, "I think we've got a Code 3 in housewares," and see what happens.
Tune all the radios to a polka station; then turn them all off with the volume controls set at full.
Challenge other customers to duels with tubes of gift wrap.
Re-dress the mannequins as you see fit.
Test the fishing rods and see what you can "catch" from the other aisles.
Contaminate the entire auto department by sampling all the spray air fresheners.
Nonchalantly "test" the brushes and combs in Cosmetics.
Take up an entire aisle in Toys by setting up a full scale battlefield with G.I. Joes vs. the X-Men.
Ask other customers if they have any Grey Poupon.
Switch the men's and women's signs on the doors of the restrooms.
Set up a "Valet Parking" sign in front of the store.
Go to an empty checkout stand and try to check people out.
Drag a lounge chair on display over to the magazines and relax. If the store has a food court, buy a soft drink; explain that you don't get out much, and ask if they can put a little umbrella in it.
