This rhetorical question is asked of someone who has done something stupid or outrageous. The point being that it is quite obvious what the person in question is like.
這是一句不期望得到回答, 只為加深印象的反問句。 當有人做了一些愚蠢可笑的事, 你就會運用到些句法。
Origin
The expression is of Irish origin although since the 1990s it has been used extensively in the UK, mostly by the young.
起源自1990年代的愛爾蘭, 大多是年輕人使用