‘屁大点’ is an informal, slightly vulgar adjective meaning 'tiny' or 'minuscule'—so small it’s almost negligible. Literally, it combines 屁 (pì, 'fart'), 大 (dà, 'big'), and 点 (diǎn, 'a bit/point'), forming a vivid, humorous exaggeration: 'as big as a fart'—i.e., absurdly tiny. It functions like a fixed phrase modifying nouns (e.g., 屁大点地方, 'a tiny place') and often carries a tone of dismissal, impatience, or playful sarcasm.

This expression is common in spoken Mandarin, especially among young adults and in casual settings like texting, banter, or complaining. While not appropriate in formal writing or polite conversation, it’s widely understood and frequently used to emphasize how insignificant something is—whether size, amount, effort, or importance. The word relies on bodily humor for effect, similar to English expressions like 'a speck' or 'a drop in the bucket', but with stronger colloquial force and mild crudeness.