Okay, okay... if you don’t get the joke, from wikipedia:
Towards the end of the 1960s the modern culture began to form in Philadelphia, Pennsylvania. The two graffiti artists considered to be responsible for the first true bombing are “Cool Earl” and “Cornbread”. They gained much attention from the Philadelphia press and the community itself by leaving their tags written everywhere. Around 1970-71, the centre of graffiti innovation moved from Philadelphia to New York City. Once the initial foundation was laid (occurred around 1966 – 1971), graffiti “pioneers” began inventing newer and more creative ways to write.