Cool someone’s heels
Meaning:
Wait for a long time.

If you cool your heels, someone makes you wait for a long time with nothing to do, so you get bored or impatient.

Example:
While they were having a long meeting, Mary was cooling her heels waiting for the results.

The show was so popular that I had to cool my heels in a long line at the box office.

Couch potato
Meaning:
A person who spends a lot of idle time sitting and watching television.

If a person is a couch potato, he/she is not active and spends most of his/her time sitting and watching TV.
He/she doesn’t do anything productive.

Example:
School children don’t play outside as much as before. Many of them are overweight couch potatoes.

Don’t be a couch potato! You’re just wasting your time.

Be cut from the same cloth

Meaning:

Be very similar, act in a very similar way

If you say two or more people are cut from the same cloth, you mean they are very alike or act in a very similar way.

Example:

When you teach children, remember that they are not cut from the same cloth. Each child has his/her own personalit

Dear John letter
Meaning:
A letter from a woman to her boyfriend or husband telling him that she doesn’t love him anymore.

If a woman writes a Dear John letter to her boyfriend (or husband), she tells him that she wants end their relationship.

Example:

His girlfriend wrote him a Dear John letter and moved to Japan .

Don’t let the grass grow under your feet.
(Not let the grass grow under someone’s feet)

Meaning:
Act now without any delay.

If you say “Don’t let the grass grow under your feet” to someone, you tell him/her not to waste time and to do something immediately.

If someone doesn’t let the grass grow under his/her feet, he/she does something right now without waiting.

Example:
Now that you know what to do, act right away. Don’t let the grass grow under your feet.

A: Do you think the manager’s already started to do something to solve the problem?
B: I believe so. He’s the kind of guy who doesn’t let the grass grow under his feet.

Be down in the dumps
Meaning:
Be very sad and depressed.

If you are down in the dumps, you feel very sad and miserable. You don’t have much interest in life.

Example:
Mary has been down in the dumps since her mother’s death.

He looks a bit down in the dumps these days. Let’s cheer him up.

She failed her exam and is down in the dumps.