Having a threesome with my roomate

I had a threesome dating with one of my roommates. We are not so close actually. My boyfriend and I were hanging out in a bar and we were talking about having a first threesome. Then we saw her. I saw her alone and drinking. I thought there must be something bothering her, so I invited her over to sit with us. One thing end to another, we asked her if she wants to have a threesome with us. She agreed. So… It was exciting.