Meaning:

“放飞” means to “let fly,” and “自我” means “oneself.” Originally, this term means to “take off all disguise and let people see one’s true self.” It’s somewhat similar to “let one’s hair down.” However, Chinese netizens have used the term in a sarcastic way when they see behaviors that challenge social norms and are difficult to understand. A neutral term, its connotation can vary with contexts.

Example:

A: 你在看什么？

Nǐ zài kàn shénme?

What are you checking out?

B: 某九零后女星的照片。

Mǒu jǐulínghòu nǚxīng de zhàopiān。

The photo of some actress born in the 1990s.

A: 怎么好像没穿内衣？这也太放飞自我了。

Zěnme hǎoxiàng méi chuān nèiyī？Zhè yě tài fàngfēi zìwǒ le。

Is she not wearing any underwear? She’s truly letting her hair down! (I can’t believe she did this!)