打肿脸充胖子 [- zhǒnɡ liǎn chōnɡ pànɡ zi]slap one's face until it's swollen in an effort to look imposing; puff oneself up at [to] one's own cost; try to satisfy one's vanity when one cannot really afford to do so:
•¶ “他真会打肿了脸充胖子!” “He's just making himself look fat by slapping his own face!”