DBNK-058 - While having a specific body part washed by my mother in the bathroom... could it lead to manual stimulation? 4 hours

While his mother was showering, the son jokingly said, "How about we go in together sometime!" and his mother replied, "Okay~." Then, his completely naked mother was in the bathroom... "I'll wash your back." A sudden nude mother offering a body washing service! The son couldn't hide his erection and his mother noticed. What did the mother think when she saw her son's strong male organ...?