Earlier, I wrote about being aroused from the embarrassment of being naked from the waist down, such as from a wardrobe malfunction or punishment. But I always liked the feeling of being naked from the waist down. Back in the old days, I had a partner who was about ten years older than me, but kinky. Anyway, at one point she moved back into her mother's house and set up an apartment in the basement. It had a bathroom, bedroom, refrigerator, and everything except a stove. The mother never came down or bothered us so we were free to dress or do what we wanted.
Being a basement, it was always a little cool and damp so we usually watched TV from the couch under a blanket. One time I was there and feeling a little frisky. While she was upstairs, I took off all my clothes except for my shirt and just sat under the blanket, which was pulled up to my chest. Suddenly, I heard voices and my friend came back down with her sister, brother-in-law, and teenage daughter. (I can't remember why.) Anyway, they greeted me and started talking to me. I just stood up with one hand holding up the blanket and shook hands with my other hand. After we chatted a few minutes, I sat down on the couch. They stayed a short while and eventually left, never knowing that I wasn't wearing any pants.
When my friend came back downstairs she sat next to me and discovered that I was naked from the waist down. She got really turned on by that and, if I remember correctly, we had pretty good sex that night. The good old days.