These retail workers have a bone to pick with some of their worst customers. Imagine you're a customer at a retail store , about to peruse the clothing section or toy aisle or garden section. But you've got your to-go coffee cup with you, and halfway through your trip, you've drunk all of it. What to do now? If you're like a surprising amount of shoppers, you'll just take the cup and leave it on a random shelf. It might be half-full or totally empty, but either way, these shoppers think their i…