Mieux vaut prévenir que guérir

Literal translation: Better preventing than curing
English translation: An ounce of prevention is worth a pound of cure

On n'est pas sortis de l'auberge

Literal translation: We are not out of the inn
English translation: We are not out of the woods

Mon petit doigt m'a dit

Literal translation: My little finger told me
English translation: A little bird told me

Tu me fais marcher

Literal translation: You make me walk
English translation: You pull my leg

Faire d'une pierre deux coups

Literal translation: To make from one stone two shots
English translation: To kill two birds with one stone

On n'apprend pas à un vieux singe à faire la grimace

Literal translation: One doesn't teach an old monkey to make a face
English translation: You can't teach an old dog new tricks

Il pleut des cordes

Literal translation: It rains ropes
English translation: It rains cats and dogs

Tourner sept fois sa langue dans sa bouche avant de parler

Literal translation: Turn the tongue seven times in your mouth before you speak
English translation: Think long and hard

L'intelligence Artificielle n'a aucune chance en face de la Stupidité Naturelle

English translation: Artificial Intelligence has no chance in the face of natural stupidity.

Comment allez-vous?

English translation: How is it going?
Literal translation: How is your bowel movement going?

Actually this one needs a little more explanation . . . this is one of the first phrases learned in your first days of french class, but the phrase originated back in the Renaissance. The complete phrase was 'Comment allez vous à la selle?', which literally translates to 'How is your bowel movement going?"

Sounds like a personal question, and it was. Back in the day of bad healthcare, the best way to figure out how healthy you were was the condition of your poop.

Thought you should know.

Avoir le pied marin !

English translation: To have sea legs
Literal translation: To have sea feet.

Déplacer des montagnes

English translation: To move mountains
Literal translation: To move mountains

Débarrasser le plancher

English translation: Go away!
Literal translation: Clean the floor.