An individual known to frequently portray their thoughts and beliefs on civil structures via the chalk method (usu white chalk).
The ideas known to motivate the serial chalker are the short span of survival of their artwork and slogans, the belief that this inherent quality does not qualify their offense as vandalism, and the ability of the method to target chalkings on random or targeted individuals.
John: Did you see that serial chalker feverishly scrambling to evade the law on Elm last night?
Greg: Must have missed it.