To wear one's heart on one's sleeve and have one's heart on one's sleeve

Fig. to display one's feelings openly and habitually, rather than keep them private. 
People who wear their heart on their sleeve express their emotions freely and openly, for all to see.

• John always has his heart on his sleeve so that everyone knows how he feels. 

• Because she wears her heart on her sleeve, it's easy to hurt her feelings.

Ahead of the curve

Similar to ahead of the pack, ahead of the curve literally refers to your position on the statistical bell curve, where the top of the curve represents the median, average result. 

By being ahead of the curve you represent the top percentile of results that either has the advanced skills or understanding that sets you apart.

to be behind the curve:
not keeping up with current thinking or trends

Right up (down) my alley

up one's street ( alley): well suited to one's tastes, interests, or abilities.- Cela me convient parfaitement, c'est fait pour moi. 

• this job would be right up your street
• Skiing is right down my alley. I love it. 
• This kind of thing is right up John's alley.

For hours on end

Four hours on end, for many hours. durant des heures

• We sat and waited in the emergency room for hours on end. 
• The children were happy to play video games for hours on end.

The final/last straw

The last straw (also the straw that breaks the camel's back). le coup de grâce, la goutte qui fait déborder le vase

• Losing my ​job was ​bad enough, but being ​evicted was the ​final straw.
• She's always been ​rude to me, but it was the last straw when she ​started ​insulting my ​mother.

to hear something through the grapevine

To hear news from someone who heard that news from someone else, to learn of something informally  by means of gossip and rumor. The information was passed person to person by word of mouth.

• I heard through the grapevine that she was pregnant, but I don'tknow anything more.

Forewarned is forearmed

If you know about something beforehand, you can prepare for it, prior knowledge of possible dangers or problems gives one a tactical advantage. Un homme averti en vaut deux

To click with someone

to catch on with someone. - le courant est passé avec quelqu'un

1. [for something] to be understood or comprehended by someone suddenly. 

• His explanation clicked with Maggie at once. It rings the bell.

2. [for someone or something new] to catch on with someone; to become popular or friendly with someone very quickly.

• The new product clicked with consumers and was an instant success. 
• I clicked with Tom the moment I met him.

Skeleton(s) in the closet/cupboard

To have a secret of any sort that you don't want revealed, a hidden and shocking secret.- un cadavre dans le placard

• My uncle was in jail for a day once. That's our family's skeleton in the closet.

Origin:

The phrase 'a skeleton in the closet' was coined in England in the 19th century. Since then the word 'closet' has become used primarily in England to mean 'water closet'. The English now usually use 'a skeleton in the cupboard', with 'skeleton in the closet' more common in the USA.

'A skeleton in the closet' undoubtedly originated as an allusion to an apparently irreproachable person or family having a guilty secret waiting to be uncovered. The close-at-hand domestic imagery of a closet or cupboard gives a sense of the ever-present risk of discovery.

At the eleventh hour

At the eleventh hour (figurative): at the last possible moment.- au tout dernier moment, in extremis

Just before the last clock hour, 12

• At the eleventh hour, the supplies reached the starving villagers.
• Negotiators reached agreement at the eleventh hour, just in time to avoid a strike.

To paint the town red

to go out and celebrate; to go on a drinking bout; to get drunk. - Faire la bringue

• They were out painting the town red last night.

Origin

The expression is American slang meaning to go on a reckless debauch, to be wildly extravagant. Originally, the metaphor applied to bonfires painting the sky or scenery red. An old Irish ballad contains the lines: The beacon hills were painted red/ With many a fire that night. 

The immediate source of the phrase may be traced to the times when a Mississippi steamboat captain would want to defeat his rival. `Paint her, boys!' he would command his men as they heaped fuel upon the fires at night, casting a red glare upon the surrounding scenery. The phrase was helped into popularity by the fact that `to paint' (ie to paint the nose red) was an old slang term for drinking. [Source: Handybook of Literary Curiosities, by William S Walsh (Lippincott 1892).]
Peter Whitehead, Shaw Heath

To get a kick out of something

get a kick out of something/doing something - profiter de quelque chose
to enjoy doing something very much 

•  Anyone who gets a kick out of horror movies will love this show. 
• I get a real kick out of shopping for new shoes.

To take a chill pill

To relax, to take it easy.- décompresser, se relaxer, prendre du recul

The best time to relax is when you don't have time for it!

• She was getting so stressed about what her boss said to her that I told her to just take a chill pill – everything would be fine.
• My wife's working so hard, she needs to take a chill pill, otherwise she'll make herself ill.

Examples from the BBC "The English we speak"

Pep talk

a talk during which someone encourages you to do something better or to work harder.- discours de motivation, paroles d'encouragement

• We got a pep talk from our coach.
• The manager gave the team a pep talk at half time.

Spoon-fed

To provide (another) with knowledge or information in an oversimplified way. - mâcher le travail à quelqu'un

• By giving out printed sheets of facts and theories, the teachers spoon-fed us with what we needed for the exam

"Spoon feeding in the long run teaches us nothing but the shape of the spoon" E.M. Forster

To battle for hearts and minds

The hearts and minds of somebody
the complete support of a group of people

• I thought the president could have done a better job of reaching the hearts and minds of the American people in his speech on television yesterday.

have/keep (all) your wits about you

to be ready to think quickly in a situation and react to things that you are not expecting. - avoir toute sa tête

• Cycling is potentially very dangerous in the city - you have to keep your wits about you.

Usually, wits.

• intelligent observation, keen perception
  using one's wits to get ahead.
  Synonyms: cleverness, cunning, wisdom, insight, perspicacity, sacaciousness, acumen.
  
• mental faculties
  to lose one's wits; frightened out of one's wits.

• scaring the wits out of: tout à fait effrayant
• to pit one's wits against sb: rivaliser d'esprit avec qn
• to have one's wits about one: avoir toute sa tête
• to pit one's wits against sb: se mesurer à qn
• to keep one's wits about one: garder la tête sur les épaules
• to frighten the wits out of sb: faire une peur bleue à qn
• to use one's wits to do sth: se servir de sa tête pour faire qch
• to gather one's wits: rassembler ses esprits
• be scared out of my wits: être mort de peur
• to engage in a battle of wits: jouer au plus fin
• to be at one's wits' end: ne plus savoir que faire
• wit: esprit,intelligence
• dim wit: imbécile
• dry wit: humour pince-sans-rire ; humour caustique
• Syn. : deadpan.
• half-wit: idiot
• quick wit: vivacité d'esprit
• ready wit: caractère spirituel
• flash of wit: boutade

Keep a/the lid on something

1. To keep something secret. passer sous silence

• It's supposed to be a surprise, so try to keep a lid on it, will you?

2. to control the level of something in order to stop it increasing, to maintain control over something.- garder sous controle 

• His forces kept a lid on unrest for nearly eight years.
• Economic difficulties continued and the government intervened to keep a lid on inflation.

To eat humble pie

to be forced to admit that you are wrong and to say you are sorry 

• The producers of the advert had to eat humble pie and apologize for misrepresenting the facts.

faire amende honorable, reconnaître son erreur, admettre son erreur

Under the radar

To slip or to go under the radar. To go unnoticed, especially for a long period of time.- passer entre les mailles du filet

• They know they're buying links and choosing to go under the radar to avoid penalties
• While the majority are well looked after, we know in extreme cases that things go very wrong for these children because they go under the radar