Lyric discussion by prettywhnsedated 

"yer so bad, best thing i ever had in a world gone mad, yer so bad"

to me, this part of the song could refer to either a person/substance. many songs about the opposite sex not just love songs can be methaphors for the relationship between a drug addict and his drug of choice and vice versa i'm in no way saying tom petty is a drug addict, but it's pretty clear in his songs that you can make certain lyrics out to be referencing drug use (ex. Learning to Fly, clearly obvious).

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