Des:When I was cleaning the bathroom with my sister-in-law, the shower suddenly fell on her and her uniform got soaked! I was fascinated by the transparent body line and underwear and accidentally got an erection! Its done! While I was talking about this, my sister-in-law also fidgeted and looked embarrassed, creating an awkward atmosphere! And while I was at a loss as to what to do, my sister-in-law suddenly approached with wet eyes! eh! a little bit! He reached out his hand to my confused crotch! My sister-in-law and I had a secret that we could never tell our parents, triggered by an unexpected erection.