Some years back there were two or three (or more) paperbacks released of (alleged) amusing graffiti. The one that stuck in my mind was the tale of a gent's urinal somewhere that had the graffiti painted over. On the now pristine wall, someone drew three columns labelled "Sport" "Politics" "Sex".

The next bloke wrote underneath "Up the Reds", "Up the Reds", "Up the Reds"...