Think about WHY your service was bad before complaining . . .

Customer (to my boss): Ya know, he was kinda rude. (referring to me)
Me: You were on the phone while I was helping you. You should be happy I didn't refuse you service.

Customer (to my boss): Ya see?

Boss: He's nicer than I am. I would have told you to get off your fucking phone.

Me: I said it with my eyes, he was just too involved with his phone conversation to notice.