So, you're saying that when a customer says a phrase with unambiguous meaning, it's excusable for an employee to misinterpret it as a similar, but more common phrase simply because they aren't actually listening to the customer? When you're taking orders, your entire job is to listen to what the customer actually says, not what you expect them to say. If you're half asleep and acting on reflex and as a result you screw up, you deserve to get yelled at by the customer and your boss, because you've failed to do your job.<p>I'm quite aware of the psychology research that's been done and discussed here recently regarding cashiers operating on auto-pilot and reflexively asking "You want fries with that?" after a customer orders fries. These kind of mistakes are common, and to be expected. That doesn't change the fact that you're being paid to not make those mistakes, and if you don't have the mental discipline to catch those mistakes, you aren't fit for the job.