have your cake and eat it too的直译是：你不可以既把蛋糕完整地保留，又把它吃掉。
这句话的原句来源为：
You can't have your cake and eat it (too).
即谚语：鱼与熊掌两者不可兼得。
举个例句如下，见下列对话：
A: So I hear you are looking for a celebrity to endorse your product. （听说你准备找一位明星作产品代言人。）
B: Yeah. Gotta be a household name like Jackie Chan or Stephen Chow. And he has to be cheap. （是啊。必须是像成龙、周星驰那样家喻户晓的明星，而且得便宜点。）
A: Duh! You can’t have your cake and eat it too! （拜托！鱼与熊掌不可兼得。）