The music's plaguing our throats alight.
But your left foot's burst and moving to the knife!

The story:

I always neglected to look in the lyrics book because the pages always makes my fingers numb, but when I did yesterday it corrected me. Thank god, because the misheard lyric sounded horrifying - diseased throats on fire and somebody's foot that's been cut open by a knife, gross!

I also thought that the second line was a reference to "The Knife", another song by the band, but as it's a misheard, it obviosuly isn't.