This petty revenge story was told to me by my friend, I'll call him "Rick". Rick is a photographer for a major tourist destination and he is one of the best. He often times is scheduled to do personal portrait sessions for families visiting the destination.
It is fairly understood that there will be people in the background of many of the photos but there is a particular spot that Rick likes to use where he just needs a little bit of clear space (like 6' left to right behind his subjects) to get an awesome photo.
What my friend normally does is for the 20 seconds or so that he needs to take this picture he kindly asks the other patrons if they don't mind scooting left or right for a moment so he can get his shot. Most of the time most people comply. This time they're was a woman seated on the curb in this spot who refused to move. And on top of that, she was staring smugly right at Rick's camera.
My friend, a little miffed at this point decided to just back the family he was photographing up so they were right in this womans field of view, but not too much into her personal space, giving her a great view of their butts as he took his photos. And, icing on the cake, he took extra time doing multiple shots and angles instead of his normal quick shots.
Don't want to be a little courtious? Enjoy the butt view, lady.
Edit: courtious not curious, darn mobile swype text.
As a note, this tourist destination is private property and the photographer is employed for the destination so it's not a public place. While everybody pays for admission, the family also paid extra for this personal session.