Incestuous brother sister relationship?

So my guy friend and I have known each other for 8 years. We have a weird relationship where we banter and make fun of each other mercilessly. One of our other friends commented on our weird dynamic and my friend responded to her that we have an incestuous brother sister relationship. It struck me as odd. What do you think he meant by that?
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+1 y
Ok, so I understand the brother and sister part because we are close and fight like siblings... but why not just say that? I'm confused about the incestuous part. We don't have a sexual relationship at all.
Incestuous brother sister relationship?
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