I once had a lady in my pharmacy drive thru get very upset that I was on the phone (with a customer) and not helping her. Even though I told her twice that I was with a customer and would be with her shortly.
I work the overnight shift at the pharmacy all by myself from 10 pm til 8 am. So if you come in at 7:30 am, you might not get instantaneous service, due to me being only one person and other customers existing.
So after she was waited on by me and left, she called me on the phone and yelled at me for a good ten minutes about how terrible my service was. I stood there and took it, like a good corporate shill, until she said this gem:
"The customer who is in your store in person is always more important than someone on the phone."
Thoroughly fed up at this point, I sweetly replied, "Oh. Well I have customers here waiting, and since they are here in person and more important than a phone call, I'm going to have to let you go. Thanks, and have a great day!" And I hung up.
The person waiting at the counter was cracking up, and promised not to yell at me. And while I was sure the lady would complain to corporate about me, I never heard anything later about it from my supervisor.