你是蠢驴用英语可以说成"you are an ass"。这个说法来源于驴的贬义语，被用来形容一个人愚蠢或笨拙。

下面是一些例句：

"Why did you do such a stupid thing? You're such an ass."

"Stop acting like an ass and listen to me for once."

"I can't believe you said that. You are such an ass sometimes."

翻译：

"你为什么做出那么愚蠢的事情？你真是个蠢驴。"

"别再像个蠢驴一样行动了，拜托你一次也听我的。"

"我真不敢相信你竟然会说出那种话。有时候你真是个蠢驴。"