Conversational Graffitti Edit Meaning

1.

When somebody writes a response to graffitti that is already on restroom wall

I used the restroom at a truckstop and somebody had written on the inside of the stall "Bush's head is so far up his ass that his sphinctor is wrapped around his neck and is cutting off oxygen to his brain". Underneath that I wrote "what brain?". This is an example of conversational graffitti.

See written, response, to, restroom