I am an almost exclusive top, but have a strong attraction to thin, hung guys. Maybe the "fetish" goes back to my HS days and this one friend. Nobody really liked him except me. He was small, skinny and average looks, but he was a nice kid, at least in my opinion, but we were not really good friends until Junior year HS, when I got my first car.
He did not own a car, so I was always going to his place to give him a ride. Over time, more and more he found excuse to go back to his room to change pants, or he was getting dressed when I arrived. He flashed his package, which I enjoyed, but at this point it was not anything spectacular. This went on and, but I really don't remember realizing he was hung.
This got a little weirder because he was hung up on his sexuality, but ultimately, one day we were driving around and he asked me for BJ -- his first sexually contact with anyone, ever. No too long after that, we had a J/O session and a ruler was handy -- 7 3/4 x 5.5, and on a 5' 8" 130 pound guy, it looked really impressive.
In a crowd, he would never stand out. He was an average student. A follow, not a leader. But me knowing he was hanging a near 8 inch cock was both a turn on, and a jealousy.
Other than these few other instances with me, he did not have sex with anyone else until he was 23. I lost contact with him after College (more like a breakup), and for a while a mutual friend stayed in contact for a few years and met his future wife.
My guess is that he has not had sex with more than 5 people in his life. In some ways, its a shame that more did not see it.
Other than his cock, my memory of him would probably just be that of a good friend that I lost contact with.
So, while I am not exclusively attracted to big cocks, a skinny guy with a big dick is a huge turn-on for me.