Well, these are among the most memorable dicks, but they were NOT the best sex:
While in college, I met a guy who was visiting my campus for a conference. That weekend we happened to bump into each other at a local gay bar and ended up having sex in my dorm room. His dick was a shocking 10" and very thick!
About 10 years ago when I lived downtown, I hooked up with a construction worker that was working in my neighborhood. Hot guy: late 40's, married w/ children type. For 2-3 weeks, I always saw him at Starbucks while on my way to work. Then one day, when I had off from work, we sat and talked-- and then somehow he ended up back at my apartment during his lunch break. This guy's dick was BEER-CAN thick. I couldn't wrap my mouth or hand around it.
In both situations, the sex was just mediocre. But what these guys were hiding in their pants was the real turn-on. I mean, what could be better than casual sex w/ a big surprise?