We can't answer that, you're best bet is to ask her what she means by it, as she is the only one that knows the true answer. If her "joking" like that makes you uncomfortable, then tell her to quit.
My friend sexually jokes with me in texts.. The thing is she's bisexual.. I am straight. She joked about tongue kissing, making out? She also thinks it is sexy when I moan... Is she just messing with me or does she really want to do these things?
Your answer is no. You said she "sexually jokes" with you. Us people all over the world does this, but if she is joking than no. Your best choice is to ask her though, just to make sure. :)
She's hitting on you. This means your friendship is over as she wants to take your relationship somewhere you don't want it to go.