Definition
To lose one's balance suddenly and fall over, often in a clumsy or uncontrolled manner.
四脚朝天（粗俗語）
He was running too fast and went ass over teakeettle.
他跑得太快，結果摔了個四腳朝天。
She slipped on the ice and went ass over teakeettle.
她在冰上滑倒，摔了個四腳朝天。
The drunk man went ass over teakeettle trying to stand up.
那個醉漢試圖站起來，結果摔了個四腳朝天。