A long time ago, my girlfriend and I were laying on the couch in her living room. We had been making out for a while and were touching each other all over. It was about 6pm during winter, the TV was on, and it was dark. Suddenly, her brother joined us in the room and sat on the chair closest to the TV. We were diagonally behind him so he couldn't see us unless he spun around. My girlfriend and I stopped touching each other, but I was still really horny. While we were all talking, I slowly started feeling my way down her pants. Her pussy was still wet, so I started rubbing her clit. I had to move really slowly so there wouldn't be any obvious movement or noise. She never stopped me. Every couple minutes her brother would say something to us and I'd laugh and respond, while still fingering her. It took about 10-15 minutes, but eventually she had an intense, but completely silent orgasm. Her body wanted to writhe up and down, but I could feel her controlling it. She was breathing very deep but staying quiet. Don't remember what we did next, but I'm sure she gave me head to repay me.