It was never much of an issue with me, but I grew up living in one room with my 3 brothers and grew up as an athlete. As I've said before, I'm not particularly well hung, at least in the length department. The size of my dick never bothered me in that context. Back when I was in high shcool it wasn't uncommom at all for the guys on my team to bring up the subject of our dicks while in the showers. We were pretty frank about it and we even compared erections. However, these were guys I had grown up with and had been playing hockey with for years, so we had all seen each other naked since before puberty for the most part. As such, we were close and such things seemed "normal". Today, on the other hand, my main nudity situations occur with my wife (and we've discussed everything related to dick size) and at the gym. I don't have any work out buddies anymore. So I don't think I'd feel comfortable bringing the subject up in front of a stranger.

To answer your question, in order for me to be comfortable, we need to have an already established friendship or such before I would be comfortable.