Ok well before you start with the pitchforks keep in mind. He is in HIS HOME... granted he should keep the doors and windows closed so people don't see him and he may not even have been aware that people could see in. I mean he has a fence that YOU were looking over. You invaded his privacy by peeking over the fence which would technically be illegal as it is called a "peeping tom". Make him aware that you caught him and he could technically call the cops on you for peeking over the fence into HIS space. BUT if you tell him in a nice neighborly classy way you can avoid drama, he will probably be embarrassed enough to make sure that his blinds stay closed. Stop acting all holier than thou and pretend like you have never done it. Stop acting like you don't even have sex. This is ridiculous. If he continues to leave the window open but is STILL behind his fence then just leave him be. He isn't sharing it with everyone. Be an adult with class, tell him, he will be embarrassed and probably close the blinds next time and then when you act like a peeping tom you wont see anything... just don't be a hypocrite.

To the person who suggested posting pictures of him around the neighborhood with the word MASTURBATOR on it...GROW UP! There are kids around the neighborhood who don't need to see that kind of thing. As a mother I would be angry seeing a personal fued infecting my neighborhood AND my kids because you want to act like a teenager with no balls to act like a mature adult.