fly off the handle 的意思是大发脾气，勃然大怒。
Eg:
1.When I told Dad I had crashed his car again, he flew off the handle. 当我跟我爸说我又把他车给撞了，他气得都快冒烟儿了。
2.Jane is trying to get to sleep, so if you wake her up she will fly off the handle. 简现在正在努力地睡着，所以如果你这个时候去把她弄醒了，她肯定会发毛的。