Yes, the grammar is bad. I would urge you to always be aware that song lyrics often have changes like these to fit rhythm, rhyme and style into music.

That line is an example of what is known as "poetic license". In poetic license, the rules of the language have been deliberately suspended for the sake of obtaining an effect. Although I do not know of this song, I suspect the character that the song is referring to doesn't care about adhering to rules, and so the use of poetic license would be entirely in keeping with that. In that case, while it is not correct, it is appropriate.