Who isn't familiar with trucks selling corn on the side of the road in the middle of summer, or some other vegetable. Corn is what comes to mind right away, but it could be strawberries or peaches, whatever the surplus vegetable is in your area. Running a website online with t-shirts for sale in the middle of summer is sort of like that only without the stinky exhaust of trucks in your face. We sit here and wait for orders with pictures of shirts hanging over the side of the website. People drive by and look sneeringly at our products, but eventually they will be hungry and realize that we have the cheapest shirts, widest variety and heck they need t-shirts, so they buy some.
The counter-intuitive aspect of all of this is that thousands of other people also need t-shirts in the summer, so the best products are often out of stock as the summer wears on. So order weeks in advance of your event if you need something different or a wide variety of t-shirts and colors, because it may not be available at the click of a button in the middle of July.