Here are the most common Brazilian Portuguese idiomatic expressions built around it, and how they’re used:
Falar sério
➜ Seriously speaking / On a serious note.
Tirar (alguém) do sério
➜ to stop taking someone seriously / to make someone lose patience.
Sair do sério
➜ To lose one’s composure / to snap.
Levar a sério
➜ To take something seriously.
Falar sério Fala sério cara! Be serious, dude!
Tirar do sério Ela me tirou do sério. (Be serious!)
Sair do sério Eu saí do sério. I lost my temper.
Levar a sério Você precisa levar isso a sério. You need to take this seriously.