My friend's girlfriend let me fuck her while she was watching us

I met my friend in the garage and we started talking about our girlfriends. I told him that my girlfriend has a big ass and he asked me if I wanted to fuck it. I agreed and my girlfriend came over. She was surprised when I told her what we were doing, but she didn't mind. We started kissing and then she took off my pants and started sucking my cock. After that, we went upstairs where my friend joined us. My girlfriend got on top of me and started riding my cock while my friend was sucking her pussy. Then, my friend fucked her from behind while I was fucking her from the front. It was a really hot 3 some. In the end, my friend came on my girlfriend's ass and I came on her big tits.