“like a dog with two tails”别理解成“像有两条尾巴的狗”，真实含义是非常高兴，非常兴奋。

【例句】
Mary's been like a dog with two tails ever since she got her promotion.
玛丽自从升职之后就非常高兴。

I never expected to win, so I'm on cloud nine.
我从来都没有预料到我会赢，所以我非常开心。