I'm a nudist. As others have mentioned having a penis that can practically disappear I thought I would tell more about that. I had read that the northern horse barbarians had evolved penises that can be withdrawn under the pubic fat pad. This is an obvious plus if you are riding around on a horse in very cold temperatures for who would want their penis to freeze off. Reproduction would surely be hindered and maybe life itself. My penis can retract completely out of sight under that pad of fat. It is entirely ordinary in all other ways, average length of about six inches and average girth.
As a nudist I have been asked by a variety of women about whether I had a normal penis. I told them that it was a special hi-tech stealth model and that a private 'showing' could be arranged. They all wanted such a private showing and were quite willing to help the changeover to non-stealth mode by persuading my penis to come out all the way.
I have even used this attribute as part of my Halloween costume at a club party, going as a nude woman. I have to shave all over to start with (terrible). I'll never do that again, it was miserable growing back in on my chest and back. Then some latex 'breast supports' doing sort of a magic bra effect. Then I withdraw my penis all the way in and use spirit gum to keep it there. Then I had made a realistic looking latex vulva which I glue over everything which gives me puffy outer labia and a pronounced camel toe with a nice clitoris. Then some auburn pubic hair to cover the seams. Everything is a realistic color and shape and blended in with makeup. A suitable wig a a feather boa with ridiculous rhinestone glasses completed the transformation. Nobody recognized me. From a distance or in semi-darkness I certainly looked like a woman and even had a couple of guys try to pick me up. It wouldn't have worked in full sunlight but in the evening with disco lights etc I could pass. I couldn't drink anything at the party as my costume genital parts had to come off to take a leak.
Just a note to anybody trying this, shave a day before using spirit gum or you will learn a new meaning for pain.