Latrinalia: The Study of Restroom Graffiti - Site Dedication to Alan Dundes. He states in his article:

Here I Sit - A Study of American Latrinalia, it is preferable to the term shithouse poetry. The word graffiti is plural of the Italian word graffito which means incised inscription or design, an ancient drawing or writing scratched on a wall or other surface. Since the beginning of time, people have communicated messages through visual means. Back then, if you were lucky, your messages etched in stone, had meaning worth contemplation. Today, some wonder whether writing in restroom stalls in an alternative mode of communications, or nothing more than the defacing of public.