être soupe au lait

You use it as an adjective to describe a personality trait. You can say il est soupe au lait or elle est soupe au lait. It stays the same for men and women. It functions just like saying someone is 'grumpy' or 'irascible'. Use it when someone snaps at a small joke. Use it when a boss overreacts to a tiny typo.

Use this when you are venting to a friend about a difficult person. It works perfectly in the office when a colleague is being difficult. You can use it at home if a sibling is being moody. It is great for describing that one relative who can't take a joke. It is a vivid way to warn someone about a person's temper. 'Watch out, he is very soupe au lait today!'

Do not use this for long-term clinical depression. It is for temporary flashes of anger, not deep sadness. Avoid using it in very formal legal or medical settings. Do not say it directly to the angry person unless you want a fight! It is a bit too descriptive for a formal performance review. Stick to 'impatience' or 'reactivity' in those professional cases.

This phrase dates back to the 19th century. It relies on the kitchen experience of boiling milk. In French tradition, many soups were milk-based. If you have ever boiled milk, you know it rises suddenly. It is a classic 'homely' metaphor that every French person understands. It reflects the French appreciation for culinary analogies in daily life. It is a staple of French literature and film dialogue.

You might hear monter comme une soupe au lait. This means 'to flare up like milk soup'. It emphasizes the action of getting angry quickly. Sometimes people just say il est très soupe au lait. There aren't many slang versions because the image is already so perfect. It is a timeless expression that hasn't aged a day.