This is something which has probably been used in the community many times before but I've been away for a while and happened to start using it myself one night so I said I'd throw it up.
I'm sure you've all played the game 'Truth or Dare' as a child so there's no need for me to explain what it is. I've found it's quite effective to use when things are already moving in a sexual direction. Think of it as a kind of transition from just normal, sexual tension stuff into actual foreplay. I'd imagine if you tried it too early it'd come off as a bit creepy.
What I'd recommend is getting to a level of sexually themed banter first (if you start off with just normal banter you can gradually start to take it in a more sexual direction). After this start moving into some sexual tension building stuff using things like innuendo, incidental kino and charged vocabulary (there's a good article on this on Vin Dicarlo's website:
http://vindicarlo.com/sexual-tension
At some point in all of this, try and get her to agree that she is an adventurous person. You could do this through cold reading (telling her she's an adventurous person in a positive way that she has to agree to), banter in which you imply that she's not adventurous and then get her to argue that she is. There are any number of ways.
Once you've done this you can pretty much go straight into the Truth or Dare and just let the escalation take care of itself. If things are already highly sexual and she's just argued or agreed that she's adventurous then she's kind of compelled to do it and things will (if you work it right) go in a sexual direction.
Like I said, this is probably something that's been around in the community for a long time already but hopefully it'll be of help to some people. Maybe some people even have some tweaks that they've found to be effective
