The whole family was on vacation and it was clear that my stepson would fall off a rock on the first day and break his hand. There he was, lying in bed in the shade at 30 degrees. When I was just about to check, I saw him trying to jerk off his big boner. I observed the situation and on the one hand I was of course sorry, but on the other hand I also had a responsibility to help. Eventually he no longer had his hand free. As a decent stepmother you really enjoy doing something like that, plus he had a magnificent cock that I would have had a hard time saying no to...