I have no sympathy for you. Customers get mad when the employee doesnt do the job right, which is really sad because all you have to do is read a sign that tells you what to put on the burger. If you could learn how to correctly read a sign and execute what it says, all problems would vanish.
McDonalds employees, if you are reading this, I hate you. I really, truly hate you. You complain about a customer because you and your pea-brained co-workers cant perform one of the simplest tasks known to the food industry, so you are really just getting mad at yourself.