In the gents toilet at the long gone Backworth Station, Northumberland, circa 1972:

Some come here to sit and think
Whilst others come to shit and stink;
But I come here to scratch my balls,
and read the writing on the walls.

And the memorable scrawl on the hoardings in Newcastle when they were tearing the old city apart in the building of the monstrous Eldon Square shopping concourse, circa 1973 (?):

Coshas the name
agros the game
bovva and agro
they both mean the same

And last, but not least, spotted on a skip in Esh Winning, County Durham, in 2003, in glorious fresh red spray paint:

The Beatles are shit