I'm going to talk about a customer at work
Do you really have to? What problem do you have with this customer?
Every time she came into the store she called me by my first and my last name and I didn't like that.
Even if you don't like her using your full name, it is still rude to talk about customers. You should be more respectful to your customers.
What if I don't agree with you and say you are trying to control my free speech?
It's fine, you don't have to agree and I'm just trying to say that there's a time and place for everything. Don't you think talking about them when they're around can be humiliating? How about waiting until you get home to have a nice rant with your friends?