Bring a big roll of stickers marked "Clearance Item: 1/2 Off!" and begin putting them on big ticket items such as riding mowers.
Bring a few hundred black ribbons to pin on things for "Death Awareness Week" and tell everyone that a portion of the purchase price goes toward "Making sure we don't forget." Put them on highly inappropriate items such as tents, fishing poles, coolers, sexy lingerie and healthy choice menu foods.
Look at a very expensive electronic item, and when a sales associate shows up, ask them to tell you all about it, but first warn them you're L. M. Bass of Schroeder, Bass and Snorgtwinkle, and you can spot a lie from a thousand yards. (L. M. Bass is short for Largemouth Bass).
Go to the superstore refreshment counter and ask them if various foods contain Polyagglutinase, claiming that it would puff out your face like a balloon and fluid drip out your nose and ears. Explain loudly that people have been known to die of this. Eat a bite of something, puff out your cheeks, plug your ears with your fingers and run for the bathroom going "eeMMHHHHHHMMMMMMMM!!!"