First time was when I had spoken to an aquaintance who then rang me a couple of days later inviting me to join her and her friend for a threesome. Most enjoyable but I learned that I can only enjoy one at a time!

Second time: we returned from a 'swinging' date and found our babysitter waiting for us in our bed so we enjoyed her. In this case since both Fs are bi I had to wait my turn on occasions.

Gus