http://www.slate.com/articles/life/food/2015/08/etiquette_for_shopping_while_your_cart_is_in_line_at_grocery_store_efficiency.html

If you live in a big city, and there’s a Trader Joe’s nearby, you probably know that rush hour there is a madhouse. Since so many urbanites like shopping for cheap, healthy (or at least healthy-looking) food in a nautical-themed atmosphere, peak hours such as weekday evenings and Sunday afternoons find the produce section packed, the aisles clogged, the refrigerated sections swarmed. Making the congestion even worse, the checkout line sometimes winds all the way around the store, with Trader Joe’s “crew members” deployed to hold flags reading “End of Line” seemingly miles away from the registers.