Dear JoJo:

Assuming he is unaware that his swimming shorts are see-through, I wouldn’t say anything at all to him. My reasons for saying nothing are:

1. He is swimming alone in his pool, no child or underaged person involved.

2. Once you tell him, you cannot un-tell him. If you tell him, then every time you see him afterwards, the two of you may have the image of his private area on your respective minds. You may have that image on your mind every time you see him for some time, but at least, you will not have a reason to believe that he has the same image  on his mind when he sees you!

It is possible though that he is aware that his swimming shorts are see-through and that he enjoys the idea of you seeing his private area, so he walks over to talk to you and to check on you, but also to expose himself in this way. If this is the case, then it will  be appropriate to say something to him. Do you think it may be the case?

anita