Frank and I used to be roommates in a first floor garden apartment near where we worked. Frank was never at a loss for bringing home women after a good night out. I was dating Mary, so I wasn't as prolific as Frank.
I knew Frank was a good lover and that he must have had a decent size cock from the very loud sounds of his sessions, that "OMGs" from the women, etc. I have to admit, I became voyeuristic and couldn't wait to listen in as Frank went at it again with someone else. One night I ran into him in the hall on the way to the john as he was leaving his room after doing some lady. Damn was he hung! He had to be about 9 inches, while somewhat flaccid. It was hanging there, swinging. You could tell that he just got done making love. Now I knew what all the OMGs were about.
Anyway, Mary moved in with us in the apartment. She and I were getting serious, close to getting engaged. Frank was always a gentleman and very nice person to her. Never came on to her, etc. It wasn't long though, before the sounds of Frank's love making and the "OMGs" came through the walls. While our sex was decent, I didn't have Mary screaming "OMG", "oh Baby" and slamming the bed into the wall. I'm about 6 inches fully hard.
The sounds embarrassed Mary and she asked if this happened a lot. I told her it did. I'll never forget one night; Frank was really going at it for quite some time. Mary asked me if this was going to go on for a while and how surprised she was that it was still going on! That's probably the first time I started thinking about seeing Frank take Mary with that big dick of his, especially from behind. Mary has a broad ass, but very firm. I got a raging hard-on thinking about how hot it would be to watch Frank pound her from behind with his big dick.
I used to try to set up situations, e.g., going to the beach together so Mary could get a glimpse of Frank's package thru a wet bathing suit. I caught her a few times catching some looks at his crotch. But nothing came from it from either one of them.