官宣

guānxuān

Literally says

official announcement

Actually means

to go public with big news, usually a relationship

When to say it

Started with celebrity couples posting official relationship news, now anyone announcing anything big can use it. New job, engagement, new cat. It is mock formal and playful, post a photo and write guānxuān and everyone gets the joke.

Hear it in the wild

他俩终于官宣了。

Tā liǎ zhōngyú guānxuān le.

They finally made it official.

我官宣一下，下周入职。

Wǒ guānxuān yíxià, xià zhōu rùzhí.

Official announcement, I start the new job next week.