laugh one's head off

例句：

1. 1.She laughed so hard that she almost fellover.
   她笑得太厉害了，差点摔倒。
2. 2. He laughed so hard that he couldn't stop.
   他笑得太厉害了，停不下来。
3. 3. The joke was sofunny that everyone laughed one's headoff.
   那个笑话太好笑了，每个人都笑得前仰后合。