To the original question: you apply sunscreen to your penis without getting an erection the same way you apply soap to your penis in the shower without getting an erection: by policing your thoughts.
If touch without erotic thoughts got you an erection we’d always get one from the mere touch of our underpants. Men do have an actual brain.
Yes, and thats what we’re discussing, how to apply sunscreen to it.
I’ve been to many swimsuit optional beaches. IME it’s really no big deal. I wear a suit because it’s more comfortable, plus vitiligo. Others are topless or totally nude. It’s really not a big deal.
Also, of course, nude beaches are a lot less sexy than many folks assume. Not everyone there is beautiful.
The few European nude beaches I’ve been to were sure-fire erection-killers for later romance with my wife. “Oh, the horrors!”
I’ve been to a clothing optional beach twice. Both times, i wandered there by mistake, and embarrassingly, it was the same beach (but a couple decades apart). Since i hadn’t planned to go to the nude beach, and only about half the people were nude, i left my suit on.
But what i learned the first time is that most people look better with their clothes on.
What i learned the second time was that my kids were immensely embarrassed by my talking to a random nude guy.
I’ve never understood the appeal of nude beaches. Everyone’s supposed to act like it’s no big deal and ignore all the nakedness, and it’s harder to enjoy the beach activities without getting sand in places where you’d really rather stay sand-free, so what’s the point really? 
You’re supposed to wash it?
With the exception of the one at Ibiza, I have also found this to be true.
Assateague Island by any chance? I went for a long walk on the beach there and out of nowhere suddenly everyone was nekid.
Martha’s vineyard.
Ahhhh.
I can safely say that none of my shower routine involves policing my thoughts. Personal care is just a different sort of non-stimulating touch. If it goes beyond that, it wasn’t by accident.
Though based on my experience at a nude beach, the main reason this isn’t an issue is that most people there are well over 30 (maybe 40). That’s an age where nobody really needs to worry about getting overstimulated by a stray ocean breeze. Under 25 y.o. however, that’s a different story entirely.
We’ll, there are different reasons for different people. There’s a nude square dance event many of my friends have gone to, and i know one very fat guy who says he finds it very emotionally freeing to in a situation where he’s not trying to hide his body. I think the feeling of “not hiding anything” is a draw to people with ordinary bodies, too.
And swimming in the nude feels really good. There’s something about the feeling of water sheeting over your whole body that’s nice. I don’t go to nude beaches, (i rarely go to beaches, honestly) but at the camp i vacation at every summer, i like to take a brief nude swim in the lake before breakfast, when the social understanding is that no one walks in front of anyone else’s cabin before 7:30. (And breakfast is at 8.) So I’m alone, or sometimes with my husband. And i do it partly to feel clean (the camp has no showers, and the “sun shower” little bag of water tied to a tree doesn’t do it for me) but mostly to enjoy nude swimming.
As for sand, they use towels, you know, between them and the beach. And they often wear sandals or flipflops. And i find sand gets into all those areas when i swim at the ocean despite wearing a suit. I don’t think it’s very different.
There’s the Austin Powers technique:
“Margaret Thatcher naked on a cold day! Margaret Thatcher naked on a cold day!”
you said it, not me.
Isn’t this more of a problem when someone else applies sunscreen to men? Or men applying it to someone else?
You’re a bad girl! 
That was established a long time ago~how do you think I found da Dope?
Fluffers exist in the industry for a reason. Just sayin’
Similar incident here. Was visiting my sister who had moved to Florida, and we took a drive to Key West. We were doing a walkabout on the island, and saw a bar with a big deck right out on the water. I said, hey, let’s check out the view and maybe get a drink! The hostess gave me a big smile and a welcome.
There was a long pier jutting out into the water, and I was walking down toward the end of it. It was wide enough that sunbathers were lounging along the side of the pier. Suddenly, halfway down the long pier, I noticed a ‘free willy’. I stopped and looked around-- dozens of nude bodies, as far as the eye could see, lounging on the deck. I had been so focused on the water view I had no idea. I looked back to see that my more observant sister was still back at the entrance, waiting for me.
After a brief moment of embarrassed panic, I slowly and calmly finished walking to the end of the pier, looked out at the water for a minute, and casually walked back to my very amused sister.