<human>: My GF and I have been together for a month, and she was drunk the other night and told me that one of her fantasies is to go down on another girl, and have the other girl go down on her.

I asked "where would I be?" and she says "behind me f*cking me".  

I have not had a threesome before, and I am not sure how I would go about finding a third to join us.

Some thoughts I have had so far:

1. Obviously we are going to discuss anything before I do it, so this is just for ideas on what to discuss.

2.  I dont think she wants to watch me f*ck some other girl anymore than I want to watch her get ploughed by some other dude.  Just from something she said another time.  So we would definitely have to discuss boundaries etc before.

3.  Guess I would prefer someone that is not a mutual friend, in case it does not work out great, we wont have to see them again.

4.  Unless anyone has a better suggestion, I would probably just end up sorting through blendr looking for a random.

Has anyone been in this situation before?  Trying to find a third to join you and your BF/GF for no-strings attached fun?  How did you go about it, and what advice do you have?

Thank you for reading.

Summarize the given text in a few sentences.
<bot>: My girlfriend has said she has a fantasy of going down on another girl, and having anonother girl go down on her.  How to find a third to join us?