Only a dumdum would leave their keys in the car.

只有傻瓜才会把钥匙留在车里。

Don't be such a dumdum, it's easy to understand.

别当傻瓜，这很容易理解。

Don't act like a dumdum, you know better than that.

别像个傻瓜一样，你比那更聪明。

He felt like a dumdum when he forgot his own birthday.

当他忘记自己生日时，他觉得自己像个傻瓜。

She called him a dumdum for not knowing how to use a smartphone.

她因为他不会用智能手机而叫他傻瓜。