Oh nice thread!
I had some experiences like this, I'll share my favorite:
-neighbor of mine in his twenties, super tall around 6'6" and swimmer build, athletic af, dirty blond hair, green eyes, lived in a cabin next to mine, separated only by a thin wooden wall. His room was actually far from that wall but sometimes he would fuck his girls in the living room of his house which was next to it. We lived next to each other for like 3 years, he had so many girls over that I lost count. Not one of those girls didn't scream like their lives were depending on it, he plowed them for hours without breaks, I still don't understand how you don't need water or something between. They would often tell him how big he was. I know of one threesome he had but it happened in his bedroom so I didn't hear everything that time. Still I know he fucked them the whole night and I know they were both 9s so we are talking about an endowed Adonis here.
I've seen him naked 4 wonderful times that have fuled my jerking off sessions thinking of him or just jerking while I heard the moanings of his girls. The 4 times were at the beach, him taking off his wetsuit after a swim. Even after swimming in cold waters his dick was super big and thick (actually never saw one thicker in real life), around 6", so I can't imagine without shrinkage. I have asked him how big he was hard and he said around 9" but he didn't know how thick he was. I have never seen a more perfect specimen of a man irl. His abs- v-line-bulge combo were to die for, so I can imagine why he was so successful with the ladies. His personality was actually one of his best traits because he could expend time with me or other normal people way out of his league, chat with us and have fun without being a prick as most people that successful would be.
One of my greatest memories of him is one time when I caught him with a hardon in the morning, I went to ask him for something and he opened his door half-asleep, shirtless and in brief boxers, he had a big hardon or at least a super big chubby. I made a joke about it and he said he didn't realize it and laughed hiding it with a giant hand. I had also joked with him about girls making too much noise and he has always shrugged and laughed at it. He was always very casual about nudity and sex. I tried to keep in touch after I moved but he wasn't as interested, logically. When I got COVID he did offer to bring me anything I needed in his car and I would have just to see him again if I wouldn't have been in a terrible state without any sex drive lol. I have memories to jerk off for my entire lifetime about those three years being neighbors tho lol.