"You always were my favorite drug, Even when we used to take drugs"
I've read this on here before, where people blast this lyric.
I actually don't find anything wrong with it.
The level of addiction to Mary (assuming it's Mary) was an infatuation beyond any drug he's ever craved.
I'm cool with that notion - especially when, by all accounts, he was crazy for her.
As for the rest of Between the Lines, i'm pretty sure he said in an interview that the lyrical approach was a "I Am The Walrus" vibe, in which words sound phonetically interesting rather than the meaning itself.
For every argument that the "Peace" album had filler lyrics, there are some gems in there.