Ok so, for a bit of background, my mother was cheating on my dad with my football coach. This went on for around 3 years without my dad finding out. When my dad was away or working, he’d often come over and he’d have sex with my mother in her and my dads bed. He was like a second father for a while. I idolised him because of his extremely manly build and hairy look, but I also really didn’t like him for interfering in my parents’ relationship. 
Anyway, my mum and I had to go to a country town for some sort of conference she was attending (she’s a counsellor). Anyway, coach came along for the ride, this time without my dad’s knowledge, or mine (the last time, dad knew he was going and they were even having a long friendly chat before we left). I wasn’t very pleased.
His son didn’t come this time as he was at his mothers house. We were in a motel room with no separate bedrooms, so it was one large room with a single bed and a queen bed. 
We were there for 3 nights, they didn’t have sex to my knowledge but I woke up to kissing noises one night. I knew it was so wrong.
Anyway, during the day, I had to spend my time with coach, as mum was at the conference. He had the idea of going to the large lake in the town and renting a boat. This was the middle of summer and he was in his short football shorts. Anyway, he decides to borrow some fishing equipment from the rental place. We hopped in the boat and ventured out on the lake, when all of a sudden I noticed some skin protruding out of coach’s shorts. It was just a slither, but his ballsac was showing. I continued to watch and he moved around and leant in different directions on the boat. His big hairy right testicle was in various levels of exposure all afternoon, from just a slither to the entire nut being exposed, depending on his seating position. We’re on the lake all day and I just had my eyes glued. He didn’t suspect a thing. I was glad he came on the trip after that.
When we got back to the motel room, he plonked himself on the couch, and I moved the lounge chair to directly opposite him, and just watched as his balls continued to hang out. At one point, his left nut was just sitting on the cushion. He got up to go to the bathroom and I instantly went over and smelt/touched where it had been. I heard the urine stream stop so I quickly got up and went back to the chair to view further accidental exposure.
This is again 100% true.