Lyric discussion by artxgoesxbang 

Cover art for Acid Tongue lyrics by Jenny Lewis

I think the meaning is pretty obvious. In fact, the first time I heard her sing this, it literally took my breath away.

To be lonely is a habit Like smoking or taking drugs And I've quit them both But man, was it rough Now I am tired

That struck me quite hard. It's so intimate. I feel like Jenny is holding nothing back.