fancy you laughing before you told us the joke.
【真没想到你竟然在还没告诉我们这个笑话,就已经大笑起来!】
e.g.
Fancy you knowing him!
真没想到你认识他!
Fancy having to get up at five a.m.every day!
嗳呀!必须每天早晨五点就起床!