The phrase "shakes a leg" is typically used to mean "hurry up" or "move quickly." Some antonyms for this phrase might include "take your time," "proceed slowly," or "linger awhile." Other words and phrases that could be considered antonyms for "shakes a leg" might include "loaf," "dawdle," "meander," "amble," or "saunter." Ultimately, the opposite of someone who is "shaking a leg" would be someone who is taking things slowly and deliberately, rather than rushing to get things done. This might be appropriate in situations where there is no rush or deadline, or where careful attention and consideration are required.