the other night while having sex with my gf we started talking about having a threesome and i told her id like to have another woman, so she said no way only if its mfm! we talked about the idea for a few minutes until she said she was only joking. im al for the idea considering im not her first and she has told me she her ex was longer and thicker which turned me on! how do i find out if she was joking or serious and any of with advice or previous experiences?