Don't be such a dumbass, read the instructions first.

别当笨蛋，先读说明书。

Only a dumbass would forget their own birthday.

只有笨蛋才会忘记自己的生日。

She felt like a dumbass after realizing her mistake.

她意识到自己的错误后觉得自己像个笨蛋。

Stop acting like a dumbass and pay attention to the road.

别像个笨蛋一样，注意路况。

He called me a dumbass for not knowing how to change a tire.

他因为我不会换轮胎叫我笨蛋。

Definition: Someone who repeatedly makes mistakes. Says stuff he believes is true, but anyone with common sense can see he's wrong. A dumbass.

某人老是不停的犯错。说着他自认为正确的话，但是任何有常识的人都会知道他是错的。真是个笨蛋。

Tsunade: Screw you, you dumbass pervert!

纲手: 你见鬼去, 你这个颠倒是否的家伙!

Not right now. We're on the plane, you dumbass !

不别现在拉你还在飞机上白痴！

You don't have to swallow every dumbass thing they espouse.

你可没必要听信任何他们支持的蠢事。

Dumbass motherfuckers always gotta come to me with some shit!

脑残的傻逼们总是想用一些傻逼的方法逼我发火!