When someone reminds you of your ex or you think someone could potentially become an ex and won't even give that someone a chance.
Friend: "You should ask him out."
Me: "Nah, he reminds me of my ex."
Friend: "So, he's ex-zoned?"
Me: "Yep."
When someone is labeled as demanding, argumentative, always REFUSES to admit that they're wrong, and are overall unbearable. Due to these qualities, whoever is in this particular zone has barely any chance at getting a romantic partner or friends.
Friend: "Can you believe it?! The guy had the NERVE to Karen Zone me!"
Me: "I mean, you are a bit demanding."
Friend: "PROVE IT!"
When someone is so insignificant, you erase all memory of them immediately.
Friend: "Who was that guy you were talking to?'
Me: "Who?"
Friend: "Oof, that guy got short-term memory zoned!"