This reminds me of when I used to work for the local community college. Every last Friday of the month, I'd have to go around campus taking down any expired ads or unauthorized ads on the walls and such.
All you have to do to get your posts approved is show up at the office I worked at and have them stamped with an expiration date basically. You could advertise almost anything honestly.
However, if it's not stamped, it gets torn down. Tearing down posters was fun as hell, so I enforced the rules without a problem.
One time I'm pulling down posters and I see someone taped a note for me that "Thanks for destroying the rave scene in [insert town I live in], asshole!"
I had the biggest smile on my face because all they had to do was go to the office and ask me to stamp the damn posters. You could advertise raves and shit if you want. Just loved it.