呵，有意思。
这句话是我们中国人的特有说法。当然不能直译了。只可意译。
这句话正话反说，依愚人之见，可以译成：how good you are! i can't love you more.
I think is so poor!
"You are a little devil!"
如果说"You are a devil!"那就有真的骂人的可能，但是你一加"little"就不是骂人了，而成了打情骂俏了。
You silly guy/girl!
you are so mean.
you're quite a bad guy.
bad guy.bad boy.
You...... Naughty dog!
我在一部外语电影中看到类似的句子，可以说："well..shut up..."
语气嗲一点就行了...hehe..
How bad you are
参考资料：009
YOU are so lovely!