When I was about 9, my sister 17, caught me streaking in the backyard. She gave me an option - tell mom or get a spanking. For many reasons I decided to take the spanking. Since I was already naked, it obviously was a bare bottom spanking. It was over-the-knee and she started bare handed but after a few swats had me get a wooden spoon. By the time I returned I was not quite hard but close and she had to move her knees apart so I could go across her lap with some comfort and she started again with the spoon. After what seemed like an amazing eternity she said I had enough. I did not get dressed and after a few minutes she mentioned it and said it was OK. She said if I liked being naked she was fine with that just don't run around outside and keep to ourselves.
Fast forward a couple of week and she asked me when we were alone in the kitchen if I had been streaking. I hesitated but said yes. She then told me to go up to her room and wait for it. I followed her orders and a few moments later she came up as well but I was still at a bit of loss as to what was really happening. She said asked "why aren't you naked? I forgot the spoon but be ready when I get back" I excitedly took off all my clothes except my underwear, I wanted to pull them off as she came back into the room. After a few heart pounding very excited moments she opened the door and just then I pulled down my underwear and stood there completely naked again! She had the spoon and say on the chair. I went over her lap and took another multi-minute spanking.
This routine went on for several more years with some interesting close calls until she got married...in the end it boiled down to an exchange of big-sister power trip and my love for being naked (and spanked!)