Most completely random product: Canned Italian Style Artichoke Salad. I'm nearly 46 years old and until today, I had no idea such a thing existed. And no, I didn't buy any. I think someone came up with that product and no human being yet has been brave enough to try it.
Item about which I most wondered if it was a product actually intended for human consumption: Decorative bottles of flavored vinegar. Some of these were enormous and garish -- a heart shaped bottle stuffed with orange slices and red pepper strips, so tightly packed I wonder if you could get more than a 1/4 cup of vinegar out.
I was too goal oriented, though. It would be more fun to go with friends or family, with the digital camera, and take your time trying to find the most unbelievable product in the store. Even better, every time you go back, they'll have new, ever more random crap!
Best find: 1 Kilo cans of Melitta coffee for $5. Melitta makes the cone filters and coffee makers, but they also sell coffee. It was my mom's brand when she lived in London. It's very good.