The infamous planks, which the captives of pirates were made to walk during the "Golden Age Of Piracy", were not made from wood. They were in fact made of celery, for two reasons.
1. If the captive was too heavy, the plank would snap before the captive reached the end, providing much hilarity amongst the crew.
2. If the captive was light, and made it to the end, the natural springiness of celery again made it much more entertaining - when the captive tried a discreet and dignified jump off the end of the plank they found themselves hurtling upwards, usually bashing their heads on the underside of the crow's nest before smashing through the plank on their way to the bottom of the briny.