My sister is super anxious and has huge breasts, so she's worried about me when I get injured or sick, so we decided to take a bath together! But she has huge breasts. So her huge breasts are touching my arm... She didn't care and washed every inch of my body! That was fine, but she even washed my dick! And her big breasts are resting on my arm! So even though she's my sister, I got excited and I was almost completely erect, and it was a mess here and there! Even though she's my sister, if she washed me in that place, I'd get a rock hard erection! And once I got an erection, well...