have at it
01
どうぞ, 召し上がれ
*Start eating your food
例
John: Here's your hamburger. Have at it.
ジョン：こちらがあなたのハンバーガーです。どうぞ召し上がれ。
02
どうぞ, やってみて
*used in speech to say that someone is welcome to do or take something
例
If you want to paint, have at it! All the supplies are still out.
絵を描きたいなら、どうぞ！すべての材料はまだ外に出ています。
to have at somebody
01
*to attack someone
例
I just knew John was going to have at Fred.
to have at something
01
*to attempt or try to do something, particularly with high enthusiasm
例
Now that finals are over, I need to have at cleaning up my room.
