I've had a friend/housemate staying with me for a while now. We are both very comfortable being in the nude or in our underwear around the house. We both sleep in the nude but me more so than him. Anyway, I usually jerk off once a day (if I'm not having sex) and most of the time at night in bed before falling asleep. It's pretty obvious what I am doing and I am sure he has heard me often. He usually has his tv on his room and usually shuts it off when he hears me head to my room, out of respect. Even though I frequently tell him not to worry about it. I'm not that quiet and that's on purpose, cuz I want to enjoy it and get the most out of my little session. Between my breathing, groans and sloshing sounds of my hand on my lubed up cock, it's obvious what I am doing. When I'm done, I get up to toss and flush the tissue down the toilet. I'd be lying if I said it wasn't a bit of a turn on.
He's walked in on me watching porn in my home office and no big deal. I primarily view it, but one time he did walk in on me but when he walked in, he just smiled and said 'Don't worry about it, it's okay.' He's been a great housemate all the way around. We talk about sex once in a while, and he tells me that he has pretty much lost interest in it. Doesn't seem to bother him at all.
One funny incident happened when he first came to stay with me and didn't realize I pulled the router plug out at night before bed. The next morning, he was calling me saying he couldn't get wi-fi. He uses it early every morning to catch the (Chinese) news. I jumped out of bed, nude, and was just softening from a major morning wood. He was absolutely fascinated with it - I think it was the 'girth' mostly. Not so much interested, but just really fascinated by it and I didn't try to hide it. We headed downstairs and I showed him what to do the next time it happens.