chase your own tail 

If you say that someone is chasing their own tail, you are being critical of them for spending a lot of time and energy doing something, but achieving nothing.

Any striving for military superiority means chasing one's own tail.

Look at me, born right down the road, and after all these years of chasing my tail doing nothing, here I still am.

on your tail

If someone is on your tail, they are following you closely or are chasing you and trying to catch you.

Juarez entered the finishing lap with Zadrobilek right on his tail. Only three kilometres remained.

He heard the wail of sirens, loud and close by. They must be on his tail at last.

We couldn't get out from under the taxes. The IRS was on our tail and we had to do something.

the tail wags the dog 

If you say that the tail is wagging the dog, you are criticizing the fact that a small or unimportant part of something is becoming too important and is controlling the whole thing.

To avoid the impression of the tail wagging the dog, the Chancellor cannot be seen bending to the wishes of a minority party.

How much should the presentation of policy shape the policy itself? Or, as I heard too many disgruntled senior civil servants complain, how much should the tail wag the dog?

turn tail

If you turn tail, you turn and run away from someone or something because you are frightened of them.

Rebels were forced back from position after position until they turned tail and fled.

My hair freezes on my neck to see her on the other side of the I get a prickle down my back I go and weak all over. Stumbling, I almost turn tail. `You have to face her,' I tell myself, trying to calm my heart.

with your tail between your legs

If someone goes off with their tail between their legs, they go off feeling very ashamed, embarrassed, and humiliated, because of a defeat or foolish mistake that they have made.

Embarrassingly, the community, led by their diplomats actually evacuated Kong in when there were fears about a possible communist attack. They came back a year or so later with their tails between their legs, having lost much face.

His team retreated last night with tails tucked firmly between their legs.

with your tail up    

If you say that someone is doing something with their tail up, you mean that they seem to be very happy or confident about their chances of success.

We'll go to with our tails up.

People sometimes vary this expression, for example by saying that someone has their tail up or that something puts their tail up.

There was no doubt that Mary Rand's performance on the first day put everybody's tails up.