One of the most important lessons you learn in high school besides history and calculus, is how to get away with running a business out of your locker.
Whether the inventory is actually illegal substances, such as weed - and unlicensed alcohol, or you're running a DIY shop full of sodas and snacks, the tenets for entrepreneurship are often developed in school halls, where students sneakily exchange goods in hopes of not being caught.
Since every school had at least one person running a black market scheme, the goods and marketing techniques range from downright brilliant to deeply bizarre.
Energy drinks in middle school. There were two kids who just happen to have parents who owned liquor stores in the town. One kid started taking stuff from their parent's supply, and selling it out of his backpack. Other kid caught wind of it and figured he should get into the game too. Honestly, the other kid finding out was the best thing for me because the market adjusted just like it should have.