Another hard one... However, after deep though (and, of course, a flick through iTunes) I finally chose this one- I listen to it when I'm happy because it makes me smile, and it's good when I'm sad because it's a reminder that even though things go wrong, worse things could happen. Plus, 'sometimes I think that you hate me, and other times I think that you find me endearing'.
Small note- it contains strong language. Still a fab song.
Stitching Leggings- Kate Nash