We were both 19 at the time. We hung out in my apartment with a mutual friend of ours, M18. We were all enjoying the night and playing the “have you ever” game. Something that was asked sparked a conversation about having sex in front of other people or online. One thing led to another and the friend wanted to watch us have sex. My girlfriend was all on board. He said he would sit in the chair and we can pretend he isn’t there. We start off kissing, striping each other’s clothes off, she sucked my dick, I ate her out. As we get further into it, she gets on top (our usual position) she starts riding me. Next thing I know is that I can feel a hand rubbing my balls. It wasn’t hers. I just pretended as if I didn’t feel it. The more she rode me, the more the hand was rubbing my balls and up the base of my dick, around the pubic area, and my thighs. It felt so good so I let it be. After a few minutes she wants to switch. I get on top and start fucking her slowly. That’s what she liked. Again, I start feeling a hand on my balls, before I could even look I can feel a tongue licking me. I turned around and of course it was him. I ignored it and kept going. I told her “I’m cumming” as I pulled out to finish myself on her stomach and pussy. I feel a hand come from around and start stroking me to finish me while I still feel my balls getting sucked on. I came so hard all over her. I could see the look on her face was confused but liked what she saw. It was a fun night!