Friend said she wants to have sex?

Ok me and my best friend were texting and I was talking about losing my virginity. So jokingly I said that we should just lose it to each other. Then she asked me how two girls would have sex and I explained to her, and she texted me back saying that it sounds good. I didn't think she was serious but I asked her if she was and she said yes, that she wants to, with me. I don't know if I should though, I don't want things to be awkward after wards. She out of state right now, and I don't know how to approach it when she gets back. Does anybody have any advice?