Verb: The art of actively lying down.
The objective of the perfect plank is to have a dead straight body, arms by side, palms facing inwards, toes down or pointed - to mimic a plank of wood.
*Variations are the vertical plank, the inverted plank, the hanging plank, multiple ply plank and many more.
that plank is awesome, it gave me wood
his legs and arms weren't straight, that plank was gammin
dude, what on the hell are you doing? just a bit of planking, care to join me?