Pull one's socks up

This expression is usually in the form of the imperative, 'pull your socks up', originally an admonishment to smarten up, probably directed at school children and/or soldiers, whose socks may have ridden down towards their ankles. It very soon became figurative and had nothing to do with socks, meaning to try harder or to do better. Both its literal and figurative meanings date from the latter half of the 19th century.