fechar a cara

You use it as a verb phrase. You can say someone fechou a cara (past tense) or is de cara fechada (the state of being). It works perfectly when describing a friend’s reaction to a situation. You can also use it to describe yourself when you are annoyed. It is a very visual expression. Think of your face as a shop that just put up the 'closed' sign.

Use it when someone is visibly upset but not necessarily shouting. It is perfect for that awkward silence after a disagreement. Use it at a restaurant if the service is terrible and your partner looks miserable. It is great for office gossip when the boss is in a bad mood. It also fits perfectly when your soccer team loses a match. Basically, any time the 'sunny' mood disappears.

Avoid using it in very formal legal documents or high-level academic writing. It is a bit too descriptive for a cold, professional report. Do not use it to describe someone who is actually crying or in deep grief. That is too heavy for this phrase. It is also not for people who are just naturally serious. It implies a change in mood, not a permanent personality trait.

Brazilians are generally known for being very expressive and smiley. Because of this, 'closing the face' is a very strong social signal. It is a non-verbal way of saying 'I am not happy right now.' In some regions, if you do this too much, people might call you a mal-humorado. It is a phrase that highlights how much Brazilians value outward social warmth.

You might hear amarrar o burro which is a funnier, more old-school way to say someone is sulking. There is also ficar de bico, which is specifically for that pouty look children (and some adults) get. If someone is extremely angry, you might say they are virado no bicho. But fechar a cara remains the most common way to describe that 'closed' look.