partir en vrille

You use it like a regular verb. You can say a person part en vrille when they lose their temper. You can also say a party or a meeting part en vrille when things get messy. It is very common in spoken French. Just conjugate partir in the tense you need.

• Ça part en vrille ! (Things are spiraling!)
• Il a complètement parti en vrille. (He totally lost it.)

Use it when a calm dinner turns into a shouting match. Use it when a computer software starts crashing repeatedly. Use it when a friend starts acting very strange or irrational. It is perfect for describing drama. If you are watching a reality TV show, you will hear this constantly. It captures that 'train wreck' feeling perfectly.

Do not use this in a job interview. Do not use it with your bank manager. It is too colorful for very formal settings. Also, do not use it for small problems. If you just dropped a spoon, you are not en vrille. Save it for when the whole kitchen is on fire (metaphorically or literally). It implies a significant escalation.

This comes from aviation history. A vrille is a spin, a dangerous flight condition. French people love metaphors involving movement and balance. It became popular in the late 20th century. It reflects a French obsession with 'l'ordre' (order). When the order is gone, the spin begins. It is a very visual way to describe modern stress.

You might hear partir en cacahuète (to go into a peanut). It means the exact same thing but sounds funnier. There is also partir en sucette (to go into a lollipop). These all describe things going wrong. Partir en vrille is the most intense of the three. It feels a bit more serious and dramatic than the candy versions.