I've got several. I think different songs represent different times in my life.
YouTube - Sia - Breathe Me w/ lyrics
Ever since hearing this song, it really reminds me of... me. Especially me right after leaving my ex. It was a time where I was terrified and I felt like I wouldn't make it. I was desperate for friends, for closure, for peace and this song describes where I was at for so long. Fragile and looking for someone to lean on.
YouTube - Gunpowder and Lead Lyrics
I may not know how to shoot, but the attitude in this song describes me perfectly. I love it so much and I feel like its really that "final straw" song.