look up any word, like cunt:

1 definition by Etyman

 
1.
The act of lying face down, palms flat against the sides, and feet together pointing at the floor. The event must take place in an odd location and shared via the internet to be considered an official "plank." It is allegedly dangerous.
Tom took a picture Bill planking on top of Sydney Opera House.
by Etyman May 20, 2011