Blood Bank

Well I met you at the blood bank We were looking at the bags Wondering if any of the colors Matched any of the names we knew on the tags You said "see look, that's yours! Stacked on top with your brother's See how they resemble one another Even in their plastic little covers"

I said I know it well

I see this as the story of how the two of them met... The may be long time friends (The way I interpret it) or this could have developed rapidly but either way this is an origin anecdote. The girl points out some bonds that are deeper than the surface, like those of brothers through blood. He looks at her and feels a strong connection, similar to that which she describes with the blood, (I said I know it well).

That secret that you know But don't know how to tell It fucks with your honor And it teases your head

He knows he wants her but doesn't know how to tell her. I don't see this as him narrating the girl's emotions I see it rather as a soliloquy of the phrase he wishes he could say to her. Or even a phrase that he directs to the listener. He realizes that the with the secret lying beneath the surface he can't be happy with her and can't see himself in the light he wants to. "It fucks with (his) honour" because he feels as if he's betraying her friendship by having these thoughts. "It teases (his) head" because when you're in love with a friend (we've all been there)... you read the smallest signs and gain hope from the smallest things. In essence, the secret and the hope that you hold 'teases your head'.

But you know that it's good girl 'cause it's running you with red

Definitely a statement he wishes to direct to the girl. He's confident she feels the same way, you know that it's good girl. It's running (her) with red is either a reference to the way she blushes when they talk, or perhaps a reference to the blood metaphor and the strength of the bond that he knows she feels as well.

then the snow started falling we were stuck out in your car you were rubbing both my hands chewing on a candy bar you said aint this just like the present to be showing up like this there's a moon __ crescent (waiting to?) we started to kiss

This is the moment where the friendship transforms. As Vernon alluded to in his live performance, this song is about being stuck in a car with the girl. A moment created by pure chance where they finally break through the barriers of friendship that have stood in their way. A platonic moment which evolves. Rubbing his hands (likely because he was cold), chewing on a candy bar shows that this action is comfortable... but you can feel the tension in the moment. "Aint this just like the present to be showing up like this" (It figures. that in the one moment that I've stopped worrying and thinking about this happening, it finally comes together). They kiss.

And I said I know it well - "allusion to the moment he first realized he loved her" That secret that we know That we don't know how to tell - "The same secret that they both held is now being revealed" I'm in love with your honor I'm in love with your cheeks - "The secret was always his love for her" What's that noise up the stairs babe? Is that Christmas morning creaks?

Not sure what these two lines are alluding to, but my thought is this is now years in the future and the song is reminiscing in a way. The two have grown old together and have kids and a family. They're sitting up late at night on Christmas eve reminiscing about their relationship, and can hear their kids still awake upstairs, potentially an anniversary?

And I said I know it well I know it well ...

He knew the truth about those deep life affirming bonds before, but his knowledge of them has only grown.

Just my take on it but I think that often the simplest interpretation is the best and often the most moving.