My foolish sister gets her pussy wet in the toilet and requests me to clean it, leading to taking advantage of her aroused naked form to have sex

My sister, being the irresponsible and careless girl she is, once got so turned on that she decided to pleasure herself in the toilet, making a mess that I had to clean up. As I approached her, I noticed her in a state of arousal, completely naked and exposed. I couldn't resist the temptation to take advantage of the situation and took her right there in the bathroom. The thought of having sex with my sister, who is not even my sister, is a bit taboo, but the thrill of it all just adds to the excitement. The fact that my mother-in-law was in the house only made it more exciting. This is a true story, not a role-play or a fantasy, and I've decided to share it with the world.