One day, I came home after work and went to my room when my stepsister was taking a shower. I accidentally walked in on her. My stepsister told me to get in with her, so I did. She proceeded to undress me and arouse me although I was already excited seeing her naked. She went down on me and we had mind-blowing sex in the shower. My mom walked in on us right in the middle, but I kept going, and we finished. We still do it today.