I understand it, but it's hard to explain why. I'm very comfortable being nude around my own gender in the locker room/shower/sauna, and I get annoyed at the overly modest guys as well. I guess it's because of the time that I grew up in when male modesty was frowned upon, not indulged in the slightest and considered effiminate. I have to admit that I feel that way too. I think when guys are overly modest around other guys (at least from my generation) they are violating a social norm, and in a way telling the other guys that they don't trust them enough to be naked around them because they are automatically going to ogle you, and do something inappropriate towards you. The other guys takes offence to this because a majority of times they couldn't give a crap about you and feel that you are being arrogant and conceited to assume such a thing. It's hard wired into guys to be competitive, so we are always sizing up the competition. Since a penis is the ultimate sign of manhood, it is the way that all guys size up the competition. By being overly modest, you are preventing that natural process from happening which again violates an unspoken but understood rule among men. I have bonded better with male friends, my fraternity brothers and men at the gym that I have been naked with (not sexual) because a guy's guard and bravado tends to come down when they are naked becasue they are vulnerable yet empowered. When that happens, true male bonding takes place.
One thing I do have to say though (which has been commented on in many other threads) is that it's interesting that guys that don't want to be seen naked around their own gender in the gym have no problem putting their nude pictures up on this website that is mostly frequented by other men. I simply believe that guys that are doing this are doing what all guys are hard wired to do through a different venue - that is to see and be seen by other men. I express that need in the gym whereas younger guys feel more comfortable expressing that need on the Internet. Either way it is the same thing, but in a different setting.
In my experience, the overly modest guys draw more attention to themselves than the guys that go with the flow, drop the modesty and get naked with their fellow man. Once you get used to it, it's really not the big deal that you think it is. I hope this helps you understand a different perspective on the issue. :smile: