You shouldn't give your employee discount to strangers.
Jane is working retail at a big box store and has to deal with lots of customers of varying degrees of politeness all day.
Jane wants customers she interacts with to be satisfied.
Jane is dealing with a particularly rude customer and follows protocol by deferring them to her manager.
Jane is dealing with an irate customer who is making unfounded complaints so Jane appeases them by offering her employee discount to their purchase.
Jane's manager handles the situation and then apologizes to Jane that she had to deal with the customer which calms Jane down.
Jane is reprimanded for this behavior by her boss as it violates the rules of her employment.