My absolute favorite customer smack down has to between a former boss lady and a crotchety fart stain of a customer* who tried to make a reservation a few weeks after leaving a $5 gratuity on a check for $102.
Boss: I’m surprised you’re calling to make a reservation. I thought you’d be calling to complain.
Jerk: No. Why would I complain? Everything was fantastic last time. I’m really excited to try your blah blah blah.
Boss: Well, in that case, I’m sorry but you are no longer welcome at our dinner service.
Jerk: What? Why?
Boss: Because you did not pay your bill in full last time.
Boss: Leaving my girls $5 on a $102 tab is disgraceful. [hangs up]