Confidence comes from understanding your sexual choices in the first place. Only you can determine these things. I know it seems easier to let your friend take the lead and just "see what happens," but successful experiments depend on good planning, even if you decide to change plans in the middle. Decide ahead of time if there will be sexual contact of any kind between you and your friend, who's going to take the lead if things slow down and who's going to do the negotiating. It's entirely possible to have a great three-way experience without sexual interaction between the women if they simply keep their male partner between them and give him all the attention. If you're not sexually attracted to your friend, this may be the more comfortable approach. It may not jibe with his fantasy of "hot bi-babes" fighting over him, but he'll have plenty of fun either way.

I don't know how you'll find the right third party, but you'll all have to negotiate boundaries and expectations before he comes home with you. Though telling him that you and your girlfriend have always had the fantasy of sharing a man between you may get the ball rolling for some guys, be prepared for some men to run the other way. Even among those who accept, their performance will vary widely. Don't let him get drunk either, or your time together will be wasted.

Once things start, respond honestly. Don't cover your insecurities with bravado or passive acquiescence. Without blabbering or being apologetic, just speak the truth: "Wow, this is a little overwhelming for me," or "I'd love to see the two of you kiss." You can also set limits as you go along. If you want him to keep his hands outside of your panties until you get acquainted a bit, speak up. He'll likely be nervous too and will appreciate the guidance. You can always ask for more when you feel comfortable.