get the lead out

Also, get the lead out of one's feet or pants. Hurry up, move faster. For example, Get the lead out of your pants, kids, or we'll be late, or, even more figuratively, Arthur is the slowest talker--he can't seem to get the lead out and make his point. This expression implies that lead, the heaviest of the base metals, is preventing one from moving. [Slang; first half of 1900s]