It doesn't matter if the recipient of constant jokes actually has that trait or not. A person with normal breath gets digs about having bad breath. A person of healthy weight gets digs about being fat. A person of normal intelligence gets digs about being an airhead. And a person who is straight gets digs about being gay.

The reason for the jokes is to throw the target off his/her game. Sooner or later, they're going to question themselves. "What is it about me that is sending off those signals? Why do they think that about me?" They DON'T actually think that. They're using it as a weapon to undermine confidence.

The most infuriating thing about this subtle undercutting is that you can't prove it. They stay *just* under the radar, so it's deniable. If you say anything, or even ask them what they meant, they can claim it's all in your imagination.