Why?

When I was in high school, I carved my initials alongside those of my girlfriend into a willow tree in the Japanese garden in Roger William's Park. 

Not the nicest thing to do to a tree but fairly romantic, especially for a sixteen year old.  

But why carve these same boyfriend-girlfriend initials into a the wooden frame of a sign hanging above the urinal in the men's room of a local restaurant?  The girl is never going to see them, but countless men will have the opportunity to gaze...