I've started this new thing where, when I go to a store or somewhere and I'm bored, I visualise ways to have some creative mischief. I don't do these, mind you, but hey, it helps me get through a boring shopping trip!
1. Every time you back up your cart, mimic the beeping noises made by the forklift. Really, really loudly.
2. If one of the workers is busy cutting something (I.e. trimming carpet or wood for a customer), poke their arm until they turn around. Then say, "Oops, I thought you were my brother/sister," before walking away.
3. Take a bunch of small, random items and put them in your cart. Then, when you are at least five aisles away, begin placing them on the shelves as you go by.
4. A lot of times Home Depot will have various mobile shelves scattered near the entrance, often with plants for sale on them. If you see one of these, ask a worker to get a plant off of the middle of the highest shelf. Then, when they hand it to you, say, "Oh, this really wasn't the one I wanted," and instead grab a plant from the lower shelves.
5. Sneak up behind folks who are on their phones and scream, "The phone monster will mindwash you!!"
....And that's all I have for today. The trip was fairly short.