还有，如果真需要这么做，最好先和cashier打个招呼，最后一定要记着付账。之前美国人不是在讨论这个案例吗？夏威夷一对夫妇带着两岁的小孩，这个妈妈当时30周的身孕，她在超市里吃了一个三明治，留下包装纸打算付账，但结了一堆东西不知道怎么就把这个忘了。出门的时候被拦下并被店家报警。然后他们就被arrested and booked. 小孩被child welfare service带走了18个小时，很夸张。

楼上的网站，我觉得这段说的非常有道理。大体意思就是有些不自觉的人吃了就会把包装藏起来，超市会因此损失钱。所以当你在超市里吃的时候，你对超市而言可能是一个潜在的贼，也许监控的人就要多花时间盯你。这段话后面还讲了为什么餐馆先吃后付钱而超市不一样，因为餐馆知道你吃的什么，知道你own餐馆多少钱。 从这个思路而言，中国也有句古话：瓜田不提鞋，李下不整冠，也是避免这种misunderstanding。 Supermarkets see a lot of theft occur that way, with people eating food and then hiding the wrappers or containers randomly around the store. Of course this doesn't apply to free samples intentionally given out by staff, but if you're taking things off the shelves and opening them in order to eat them, there's no way for the store's staff to know whether you're stealing unless they follow you the entire time you're there until you leave the store without paying. You look identical to a thief, so you might just get treated like one. I personally saw a lot of that kind of theft when I worked at Walmart and Target. Store policy typically opposes the practice because it is indistinguishable from theft. Even honest people who intend to pay forget sometimes, and with thousands or tens of thousands of customers coming in each week those few dollars here and there can add up to hundreds of thousands of dollars per year. The store probably doesn't care about prosecuting the four year old who gets into the candy when his mom wasn't watching, but they are interested in keeping those "shrink" costs down. Supermarkets are different than restaurants; supermarkets don't know what you're buying until you get to the cash register but restaurants know how much you owe the whole time. You have a chance to ditch the evidence that you've eaten anything in a supermarket, but there's no such chance in a restaurant. There are also no servers keeping an eye on supermarket customers to ensure they don't dine-and-ditch. Even so, both kinds of businesses lose a certain amount of revenue to people eating without paying. When dealing with a large number of customers, dishonesty becomes predictable; you never know who will steal, but you can predict what percentage of your revenue will be stolen most of the time. Part of the reason that membership stores like Sam's Club and Costco can offer lower prices than supermarkets on many products is because their shrinkage costs -- especially theft -- are much lower. People are less likely to steal things when the staff knows who they are because they had to show a picture ID to get in. If stores ostentatiously allow eating of food before its paid for, they have already decided to accept more loss to theft and shrinkage in exchange for the increased business they can expect from convincing the customer they respect them. It's a business decision, and different businesses will make the decision differently. All in all, I advise against eating food until after you pay for it. Even if you fully intend to pay for it and absolutely certainly will not forget, you're still making it harder for the store to prevent theft and, therefore, more expensive to run the business. Why do that to people if you don't have to? There are exceptions; if you're a diabetic whose blood sugar is crashing, yes, please go ahead and eat. But if you're just impatient, exercise patience.