You're probably already familiar with the words "quickly," or "immediately," or even "instantly," but have you heard of the phrase "at the drop of a hat"?
It means to do something immediately or instantly, without stopping to think.
When you drop your hat, you react right away: "Oh no!" You wouldn't want something that you usually wear on your head to be on the ground, so you try to pick it up right away.
Some of our teachers will laugh at the drop of a hat. They find lots of things funny and react instantly.
Is there anything that you do at the drop of a hat?