This phrase is used to describe lucky persons, but it uses an animal.

Oh, about this question I only know lucky devil

I looked up the dictionary... Lucky dog?

回复 @圆环之理：Yeah! That's right.

回复 @圆环之理：And thanks because I learn a new phrase. Then how about giving us some quizzes?

回复 @啊啊是谁都对：I am a little curious. In most cases [dog] is used as swearwords, but now it is used to describe a lucky one. (But actually in German there also exists the similar case. They use [pig] to describe an unexpected good luck)

回复 @啊啊是谁都对：Let me see

回复 @圆环之理：That's quite a interesting question. Let me see.