She’s your friend dude, just simply ask her. There is nothing to feel awkward about. I and my best friend have always fantasized hot sizzling and steamy threesomes and finally tried it too. Best experience of my life. Maybe just send a text and see the response? Or start a conversation where you can ask about her weirdest fetishes. Oh maybe start with a game of truth and dare and make her spill out the beans. This way you will not even feel embarrassed and your query shall be answered too. Once you find out then play accordingly. You can either ask her directly or just send her a booking, trust me this can turn on a lot of youngsters.I would aroused just by the thought of it. I would be ever willing to replace your friend if you do not mind a stranger, I’m quite nonjudgmental too so it will not be awkward for you either.