Though there is no dispute that songs may have nonsense lyrics, the song "Seven Nation Army" by the White Stripes actually have very coherent lyrics.
However, one line stands out as some type of idiom that I cannot decipher:
And if I catch it coming back my way I'm gonna serve it to you.
I infer that this is some type of threat, both by the "I'm gonna ..." and also by the context of the rest of the lyrics. But what is "it", and what does "serve" mean? Perhaps "serve" is to "return the (it) back to you"?
Surely Jack White didn't just throw in a single nonsense sentence to an otherwise very coherent and well-focused work.