Play it by ear

Another way of saying "go with the flow." Usually used when there's no set plans and everything furthermore will be done when it's done (or spontaneously).

to do something by feel and instinct rather than with a plan, to improvise

-To let things go as they may.
-It is usually said when a person who is asked a question is not quite sure as to what to answer with.

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.

Letting you down politely, when you ask someone to do something and they want to do something, just not with you, they will say they're going to "play it by ear".

to put off a decision till later

We say play it by "ear" because we are making decisions as we HEAR them. This means we are not making any final plans right now because we might hear of other things that could prevent us from being able to participate. So basically it means I might have better shit to do.