When I was a student, I lived in the dorm and my parents paid for everything. I dated a guy that regularly came to my place and emptied my fridge. I decided to try a trick: I took him to the grocery store. I got some food, and so did the guy.
When it was time to pay, he stepped away to prevent people from thinking he was going to pay for the food. I asked him to pay and he did, but when we left, he asked me when I was going to pay him back. I told him everything I thought about him. And he said, “I had no idea you were this greedy.”