Lyric discussion by NihilisticIdol 

Cover art for K lyrics by Jana Hunter

I interpret this as a falling-in-love song. More specifically, the narrator feels frustrated with his/her emotions of attraction towards another and seeks to vent these emotions through music, presumably a mixtape.

Evidence: The line "Mix me with a stereo song" could refer to some association between song and the narrator, such that the feelings of the narrator are expressed to the love interest through the songs he/she puts on the mixtape. More conclusively, the lines "No place to vent this frustration/elation / and I'm pulling all my hair out / So I made this compilation" reference a "compilation," perhaps a mixtape.

As far as the repeating backbone metaphor goes, the backbone could be seen as a symbol of the narrator's love interest, such as "to hold your backbone in my hands" would occur during a hug between the two.

The last thing I noticed is that for the narrator to "see you Saturday afternoon / I'd stick around and go with you to church" creates an ironic contrast between the implied sexuality of spending the night and going to church the next day, Sunday.

This is indeed a strange song, especially from the Jana Hunter cannon. Musically, it is her only song even remotely electro-pop, however, the abstruse lyrics are characteristic of much of her other work.