My sister sent this picture to me today. She goes to school at the University of Wisconsin-Madison and this was found on the walls of one of the bathrooms.
It reads "Ministry of Magic Employee Entrance."
For those non-Harry Potter Fans, the Ministry of Magic is the governing body of the magical land Harry and his friends and enemies live in. Apparently, this graffiti artist presumes they exit via bathroom Napkin Disposal.
I never finished the Harry Potter series after I read three of them back when I was 12. Maybe I should...