Interestingly, that reminded me of one of the times I went next door to play with the oldest of the 3 kids next door; he was a year older, but we had been best friends since I was 6½. Not long after they moved in, his parents bought him a small wooden fort in the style of the American Old West, complete with ground level open area, a gate, & an upper deck with a small covered "room." We did lots of things there; but, this time, being summer, I was about 15, and showed up barefoot & wearing only shorts. A few minutes after he & I went through the fort's gate, I dropped my shorts, stretched, & said, "Ooh, this is so good!" Realizing I was making no attempt--sunlit but hidden from the yard & between their house's windows--to pick up my shorts, he started to say something, but I convinced him to shed his shorts & T- shirt, too. I said, "See how the sun feels so much better?" When I saw the other kids had left the back yard, I said, "Come on!" & climbed the short ladder to the upper deck. After sitting up there nude together and talking usual kid nonsense, I showed him how we could both lay out nude in the sun side by side with his head by my feet. After half an hour or so, I sat up so he did, too, with a huge grin from having discovered something new and told me he'd have to sunbathe nude whenever he could. But, being a teenage boy, I was starting to get horny; so, I casually started stroking my hard dick without changing the subject. But, he soon couldn't ignore what I had to do & couldn't help but get hard himself; I was a bit surprised to see his prick wasn't quite as long or thick as mine. I leaned back to be fully sunlit and started stroking with my whole right hand. After he had been speechless & mesmerized for several minutes, I smiled & said, "Don't just be a spectator. Stroke yours, too!" His hard dick was pointing up at the sky, but he still wouldn't, I guess surprised I would do that. So I reached with my other hand, stroked him myself, then moved his hand to his dick. "That's better, now, isn't it?," I said, to which he nodded yes. We had done so many things together, so I knew this was overdue. After maybe half an hour, I told him to get down to ground level so that I could show him something. Facing the west & the sun, I lay with my legs straight out on the flat boards of the upper level, out my hands under my thighs, and pulled myself forward until I was sucking the head of my own prick. With a great side view, his jaw dropped with astonishment. After a few minutes, he finally said, "Wow!!" I sat up, laughed at his reaction, and said I had just learned how to do that. (I couldn't self-suck regularly for another year and did so, usually taking 2-5 inches, until I let my back get too stiff at age 53. It was almost a year before he could also suck his own cock, too.) So, I jumped down to ground level, started stroking in full sunlight with both hands, and said, "Come on! You, too!" So, he got on the opposite side so we'd clearly see each other but sometimes would pause just from watching me. I'm guessing it was 15-20 minutes later when we were both stroking hard & fast that I convulsed, shoved my cock forward, shot a huge load of at least 12 cumshots, heard then saw him shooting his load, and then saw that my first 4 cumshots had hit him on his chest & legs, which had immediately made him cum. I laughed out loud & apologized for not telling I cum a lot (and still do) and had hit the wall several times beyond the commode at home, but really didn't expect to shoot that far. So, after several minutes, we went out still naked into their back yard so that I could use the water hose to wash my cum off him. We went back into the fort until the sun dried us out. We managed to get naked several more times & occasionally jack off together, but life started getting in the way. Again, that probably doesn't count as taboo; but, the previous recollection reminded me of this one, and our families' adjacent yards were one big yard for us 6 total kids for many years.