tǹg-tuā-ku頓大龜

to fall on one's bottom

to fall on one's bottom; to sit down hard

English Wiktionary, “頓大龜” (CC BY-SA 4.0) — https://en.wiktionary.org/wiki/%E9%A0%93%E5%A4%A7%E9%BE%9C · confidence: Medium (Wiktionary, Hokkien)