Can be a derogatory term used to describe the skin colour of someone who's skinn resembles the colour of wood. Is also used to call people stupid/dumb.
Intended as an insult, used to describe a person who might be slightly stupid/dim. Irish slang for 'moron'
Person1: Hi... This... is... my... first... time...in... Japan... How... are... you... all...?
Person2: Ya plank, most of the people here speak English!