The message of this song is if someone is trying to put you in a box, go get the crowbar, smash their box up and just be yourself. Frank Carter explained to Kerrang:
"It's about trying to be able to live in this world where everybody is trying to tell you what you should do, what you should wear, how you should talk, what music you should listen to. Everybody is so obsessed with making things right for you that actually they ignore what you really want to do."
The song was released as the lead single from End of Suffering. Carter explained: "I think 'Crowbar' is just the perfect start, because the record's quite heavy in lyrical content particularly, and this is one of those songs where it has a good statement, but it's also not too bleak. We don't want to break anyone's heart just yet!"
"Sloop John B" is a traditional West Indian folk song, and it was a huge hit for The Beach Boys in 1966. They tweaked the lyric, "This is the worst trip since I've been born" to "...I've ever been on" as a wink to acid culture.
David Bowie's "Space Oddity" tells the story of an astronaut who cuts off communication and floats into space. The BBC used it extensively in their coverage of the 1969 moon landing - an odd choice considering the lyrics.