do something at the drop of a hat
毫不犹豫迅速行动
口语·表示毫不犹豫立即行动
英文释义
to do something immediately or without hesitation
例句
She would help you at the drop of a hat, no questions asked.
典故来源
源自19世纪美国西部，当时帽子落地常作为决斗或赛跑开始的信号，表示立刻行动。