I was lying in my bed, and it was around 2am. I couldn't get to sleep, so I was watching reruns of 'Roseanne' on television, since it was the only decent show on at those hours on cable tv. While watching, I heard my brother right next door in his room.
I turned down my tv, and heard him saying things like, 'Oh yeah..' and 'Oh my GOD yeah.' He was clearly masturbating. I've been masturbating for about a year now. I quickly took off my panties (I was wearing PJs where the bottom was a skirt) and immediately started to rub my clit. I got so aroused just by the sound of my brother's moans that I could clearly hear. I imagined him stroking his dick .. it raised in front of his face, lying down on his bed. It was amazing. My tits were so hard. We were both about to cum at the same time. I heard him finally let it out and knew his load had exploaded. A few seconds later, I had climaxed.
I can't wait until the next time I hear my brother. It was definitely one of the best masturbation sessions I have ever had.