From 維基詞典
break bad有兩種意思：
事情或人的命運走下坡路, to go downhill.
特指人變壞，（of a person）to go bad, to turn toward immorality or crime. 這來自於美國南方的俚語。
breaking bad這部美劇，作者Vince Gilligan說 break bad 的意思是 to raise hell , to raise hell的意思是飲酒狂歡。作者本身並不知道 break bad 在美國南方俚語中的意思。
下面這壹段來自Time雜誌：
/2013/09/23/breaking-bad-what-does-that-phrase-actually-mean/
Show creator Vince Gilligan has said that he had
thought it was a commonly used phrase when he decided to use it as a
title, not knowing that the expression was a Southern regionalism from
the area in Virginia from which he hails. It means “to raise hell,” he
says, as in “I was out the other night at the bar…and I really broke
bad.”