Is This Flirting?

So my boyfriend has this female friend from High School that he swear is like his sister. But I'm seriously Wondering if they are Flirting. Here's an example. He was texting her a few days ago and this is on the lines of what was said.

Him: Can you bring me some free pizza(she works at a pizza shop)

Her: No

Him: Boo you whore

Her: Oh I'm a hoe. At least I've never gotten an STD like some lazy ass person. Btw does it still hurt to take a piss? (He got an STD back in college).

That just came off flirty to me. Another example she sent him a picture of what her daughter did to her hair.

Her: I'm never letting my five year old do my hair again

Him: Why you so bold headed though

Her: Fuck you

Him: Seriously why you so bold headed 😂😂😂

Her: I'm not talking to you anymore rn

Is this Flirting. It just makes me feel like it is. What do you guys think?