A call made by those who partake in the sport and world known game "planking" to advice others that the person has found a location to "plank" on. As soon as the call is heard the plankers photographer springs into action and takes photographs of the plank to display them on the web.
Caw Cawww was originally invented by the UPPA also know as the United Plankers of Plymouth Association.
The best way to get people's attention is to CAW like a bird at them.
Or
A noise that pops into people's heads when they are bored and happen to know people who like to caw.
"Dude, it was so weird! This girl walked into my class and cawed at me, then just left!"