do a number on

Meaning

Verb

• To damage; to treat harshly; to produce ill effects in.

Origin

• The origin of the saying "do a number on" someone dates back to the late 19th century as boxing was growing in popularity. The saying refers to how different types of punches were assigned different numbers. Announcers would say this when a fighter was dominating his opponent. It is now used in a more general sense.