play it by ear

When you do not have a plan, or instructions. When someone is not going to follow a direction or plan, they are just going to figure it out as they go alone. The saying derives from a musician being asked "Do you know how to play the song....." . Although the musician has no music sheets or formal note instructions, since he/she has heard the song before he/she says "No, But I can play it by ear" I child sitting at a piano figuring out them self how to play marry had a little lamb with no instruction is an example of "play it by ear" The term now is used for all sorts of reasons, if your not sure how to do something, or what you are doing, but are happy to just figure it out as you go along.