I am a 19 year old female who goes to college, but this happened when I was home on break after finals.
My brothers and I were home alone because my parents were at work. My brothers are both 16 (twins). They're pretty handsome (though I wouldn't think of them as the hottest guys around). Both are approximately 6'1', 180ish pounds.
I was walking to my room upstairs when I passed their shared room. The door was slighly open so I peeked in to see what they were doing, without announcing myself. When I did this, I saw both of my brothers naked, sitting on one of the beds and slowly rubbing their boners, which were eight inches (I heard them talk about the size, I can't tell myself). There was a porn movie playing on the TV in their room, and it looked like they were both watching it. I looked for a minute, getting really horny. I was about to leave to masturbate myself when they scooted together and started jacking each other off. They spat on their hands every once and a while for lube.
After about 20 minutes, one of my brothers announced he was going to cum. He stood up and pointed his dick at my other brother as they began to touch their own dicks again. My standing brother continued to stroke until he grunted and I saw a stream of cum shoot from his penis and hit my other brother who then shot as well. I could smell the cum and it smelt awesome. After a minute of just panting, the boys got some tissues to clean themselves up.
I then went to my room and masturbated...what an orgasm!