When my sister washed my back in a small bath... My little sister is still too young and innocent and wants to take a bath with me! When my little sister forced herself into the bath and washed my back, her breasts were completely exposed and her nipples were touching my body! When she did that, I got a full erection! When my little sister noticed my erection, far from being disgusting, she rubbed her small breasts against my arm and got horny! Then she said, "Your brother's... it's so big," and touched my dick, leading to an unexpected divine development!