To waste energy on a lost cause or a situation that cannot be changed.
To beat a dead horse.
To make someone very irritated or angry.
To drive someone up the wall
To have other or more important matters to attend to.
To have bigger fish to fry.
To solve two problems with one action.
To kill two birds with one stone.
To cause a conflict or difficult situation to worsen or intensify.
To add fuel to the fire.
A complex, troublesome situation arising when a decision or action produces considerable subsequent problems
To open up a can of worms
To make a painful experience even more painful for someone.
To rub salt in the wound.
To listen or watch out for new information or trends.
To keep your ear to the ground.
To assume something is exaggerated and not take it seriously.
To take it with a pinch of salt.
A foolish and hopeless search for or pursuit of something unattainable.
a wild goose chase
To try every possible course of action in order to achieve something
To leave no stone unturned.
To exaggerate the importance of something trivial.
To make a mountain out of a molehill.
To happen very rarely.
To happen once in a blue moon.
To waste one's efforts by pursuing the wrong thing or path.
To be or not be accountable for something.
To be on/off the hook.
To do more than one is required to do.
To go the extra mile.
To take an opposing viewpoint or raise an objection to a claim merely for the. sake of argument.
To play devil's advocate.
To have a grievance that needs to be talked out.
To set a limit on what one is willing to do or accept.
To draw the line.
Just barely, very narrowly
by the skin of your teeth
To proceed instinctively according to results and circumstances rather than according to rules or a plan.
To play it by ear.
To get to the point.
To cut to the chase.
To have an idea or plan which you have not told anyone about.
To have something up your sleave.
To allow someone some leeway in their conduct.
To cut someone some slack.
To do something which makes it impossible to return to an earlier state.
To burn your bridges.