What does it mean when your crush jokingly insults you?

As the title says. Is this a sign of flirting? He calls me fat when I'm actually slim or " ugly" but I know he's just joking. He's 29. Do all 29 year old males act like this?

And no he's NOT gay. He def likes the ladies.
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He also jokes about my size because I'm quite short calling me "tiny" and the more I think about it, the more I believe its his way of flirting. He doesn't do this to our mutual friend who is also a girl. Sometimes it bothers me but I just brush it off.
What does it mean when your crush jokingly insults you?
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