walk the plank
Be forced to resign, as in We were sure that Ted hadn't left of his own accord; he'd walked the plank. This metaphoric idiom alludes to a form of execution used in the 17th century, mainly by pirates, whereby a victim was forced to walk off the end of a board placed on the edge of the ship's deck and so drown. [Second half of 1800s]
Dictionary.com presents 366 FAQs, incorporating some of the frequently asked questions from the past with newer queries.