Being the seventh soon is a blues reference used a lot as being the seventh son is supposed to be special (I read it somewhere ages ago, but I can't remember why).
It's just a coincidence that Jack is also the seventh son, and being a worshiper of the blues he'd definitely slip it in.
Other than that, whether 'ball and biscuit' is a microphone name which the White Stripes tured dirty or not, this song is one hundred per cent sex. You don't even need the lyrics, you only need to hear that riff. It's a very very sexy riff.
Being the seventh soon is a blues reference used a lot as being the seventh son is supposed to be special (I read it somewhere ages ago, but I can't remember why). It's just a coincidence that Jack is also the seventh son, and being a worshiper of the blues he'd definitely slip it in. Other than that, whether 'ball and biscuit' is a microphone name which the White Stripes tured dirty or not, this song is one hundred per cent sex. You don't even need the lyrics, you only need to hear that riff. It's a very very sexy riff.