Literally this term means “to have one’s defense broken.” It’s originally used by gamers to refer to the scenario where one player’s defense is broken and can therefore be easily injured or killed. Chinese netizens use the term jokingly in situations where one person feels hurt by another’s quibbling and gets really annoyed. People can also feel “sour and offended” when another person brings up a sad topic related to them.
Nǐ zěnme zhèliǎngtiān fàngxué méi qù lìlì jiā yīqǐ xiě zuòyè？
Why haven’t you been doing your homework after school together with Li Li at her home?
Yīnwèi tā wánxiào kāi de guòtóu，shuō wǒ ànliàn bānshang yīgè nánshēng，wǒ bèi pòfáng le。
Because she made an out-of-line joke about me having a crush on some boy in our class, and I feel really annoyed.