A bit of wisdom for those who work in customer service:
Never talk shit about a customer. Ever. You never know who will be listening.
You might have thought you hung up the phone, but you might still be on the line with the customer. You might accidentally type into the wrong application and send the insult to the customer. Even if you’re completely alone at a shopping mall five states away, it’s still possible that a manager from your company could be within ear shot and hear you.
Just don’t do it unless you’re in the privacy of your own home.