Songfacts®:

• Bono told Rolling Stone: "It's kind of like this album's 'Beautiful Day' - it has that kind of joy to it."
• The song centers around the line: "I'll go crazy if I don't go crazy tonight." Bono noted to Q magazine February 2009 that the lyric, "sounds like a T-shirt slogan to me."
• The Observer Music Monthly February 2009 asked Bono to explain the lyric: "Every generation has a chance to change the world/ Pity the nation that won't listen to you, boys and girls." The U2 singer replied: "Well, that is building up to the next line, 'The sweetest melody is the one we haven't heard.' That's just a nice thought. The solution to the problems we find ourselves in will have to be found by the new generation but often the new ideas just aren't listened to. That lyric is meant to be playful, by the way, not earnest in any way. There's a lot of mischief on this record."
• The Black Eyed Peas' will.i.am contributed additional keyboards to this track. Adam Clayton explained to Mojo magazine April 2009: "Will helped early on in the arranging of the demo ideas in the summer. Then when he came in we recut it and he helped us push it up the hill. The final version is a recut that we did late on when we'd kind of played it in a bit. But he's a lovely, inspiring man to be around."
• This started out as a Brian Eno song called "Diorama." U2 then reworked it with the help of producer Steve Lillywhite.
• This song and "Breathe" are the only two tracks on No Line on the Horizon for which neither Brian Eno nor Daniel Lanois have a production credit.
• The hook-up with Will.i.am came via Jimmy Iovine, legendary head of Interscope Records in the US. Guitarist The Edge told The Independent on Sunday May 17, 2009: "We'd heard how great he was to work with, and I think Black Eyed Peas are a great band. I've been thinking for a long time that hip hop and R&B production is really more innovative than rock 'n' roll production these days. And we just really hit it off. Will was amazing – in a few hours he'd taken the demo of 'Crazy Tonight' up several notches. It's just a different [musical] sensibility, and I learnt a lot from him. He's got an amazing instinct, particularly for rhythm."
• This was the third single to be taken from No Line on the Horizon.
• The song's animated video was directed by artist David O'Reilly, whose résumé includes the films Son of Rambow and Hitchhiker's Guide to the Galaxy. According to the U2 official YouTube page the video's concept is that the animated characters are living meaningless lives. They realize that they will go crazy if they don't go crazy tonight, so they all "decide to make a change in their lives."