My best friend has no shame. He never has, and never will. It was not uncommon for him to streak through our apartment completely naked, regardless of who was there. Growing up, I was forced to be MUCH more reserved than that.
One evening when I got home from work, I took a shower, and came out of the bathroom in nothing but a towel wrapped around my waist. I stopped in the kitchen to grab a glass of water and while I was standing there, he yanked my towel off of me and ran away with it. I, of course, chased him down and retrieved it. Before he gave it back to me, he said "now you can quit being so fucking shy around me. I've seen your cock. You have nothing left to hide". We both laughed, and I never did the "towel dance" through our apartment in front of him ever again.
He's 100% straight and is married with kids now, and we never had a jerkoff sessions or anything like that, but it was definitely liberating to finally shed the shame of nudity that was instilled in me growing up in a very conservative household. Even now that he knows I'm gay (he didn't find out about that until a few years later), he still has no problem being naked in front of me.
I'm not so bold as to walk around naked in front of any of my other friends since then, but I am much more likely to walk around in my underwear in front of my friends than I was back then.