Some people call it boundaries but I call it self love. If someone is disrespecting you, even unintentionally, it's up to you to show them how you want to be treated. Communication is key. No passive aggressive behavior. I agree.
My father taught me to be nice first because you can always be mean later. But once you've been mean to someone, they won't believe the nice anymore. So, be nice; be nice until it's time to stop being nice, then destroy them.