Because you're stupid
笨───stupid;你───you
"Well, then Francesca turned round and said, That's a stupid question." — "She would, wouldn't she."───“嗯，接着弗朗西丝卡转过身说，这个问题问得真蠢。”——“她肯定会这么说，不是吗？”
They were stupid not to follow your advice.───他们不听你的劝告真傻.
Many of us do stupid things in our youth, but we should have the good grace to admit them.───我们很多人在年轻的时候都会干些糊涂事，但是，我们应该懂得承认错误。
The defence conceded stupid goals through sheer carelessness.───防守队员完全因为粗心大意而造成了无谓的失球。
My message is "If you try to smuggle drugs you are stupid".───我的意思是“你要是企图走私毒品，你就是一个笨蛋”。
He's a rather stupid person.───他是个二百五.
I suppose it's stupid of us not to be able to make up our own minds.───我们自己都没办法拿定主意，这真是太傻了。
A stupid fellow is talkative; a wise man is meditative.───蠢人饶舌, 智者思虑.
I was stupid enough to believe him.
When stupid man is doing something he is ashamed of, he always declares that it is his duty.
That was a stupid thing to say.
I'll never do anything so stupid again.
He is as stupid as a donkey.