Why does my coworker tease me so much?

Recently I started working a little bit in a new department. there's this girl who I've talked to a few times but its just chit chat. Recently she has been giving me a LOT of "crap" when we are working together (calling me lazy and things like that) we go back and forth a lot, its funny and enjoyable. Usually I'm just minding my own business and she'll come up to me and start stuff, I have never started anything but I usually play along. I know some people are friendly by nature but its like she is way too comfortable calling me names and stuff and she is always asking me questions... Is she just friendly? There are more people around but I have never seen her act like that, in fact, a lot of girls there are always talking to me, I keep to myself but they always find a way to get me talking.
Why does my coworker tease me so much?
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