My latest post, which happened to involve food, got more visits and acclaim than my typical posts. In fact, one reader explicitly said that food based finance was more accessible. So, let's try it again.
The term arbitrage is common in the finance industry. Performing arbitrage is profiting from the variance in prices in the market. Take the vanilla bean example in my last post. Imagine that the big grocery store had a really liberal return policy, and they would let me "return" vanilla beans with or without the original container at the price of $16 for 2 (the price they sell them). I could go to the local spice shop, buy 10 beans for $20, and then go sell them to the grocery store for $80. I keep the $60 as profit and have successfully arbitraged.
This helps explain why many stores require a receipt and/or original packaging to accept returns.