Well, to be fair, he came up with it while driving back after dropping them off. That’s not the point though. In a recent interview with Triple M’s Ugly Phil, Grohl recounted the story of how he came up with the riff for the song ‘La Dee Da’ off Concrete and Gold:

 “I remember coming up with that riff in my head as I was driving back from taking my kids to the bus stop...And I hummed it into my phone. And that's what I sometimes do, I'll hit the voice thing on my phone and just hum these stupid riffs. I've got a million of them and it sounds so weird to hear me going like that.”

Foo Fighters

He then took it to Greg Kurstin, the man whom the Foo Fighters recruited to produce the new album. Given Kurstin’s past (award-winning) production work for acts liked Adele, Sia, Kelly Clarkson and Carly Rae Jepsen, Grohl thought he’d need to be pushed to produce the song in true Foo Fighters style.

According to Grohl, “We told Greg 'We want this to be really thrashy and noisy.' And I sort of felt like we had to push him in that direction, and then he'd go like 'Oh, okay.' And he'd set it up to the point where it was so f****** noisy! I was like 'No, no, no, no, no... Dial it back a little bit. I know you're the f***** Adele guy, come on!'"

Listen to the Greg Kurstin produced ‘La Dee Da’ on the Foo Fighters’ latest album Concrete and Gold. The band has also announced a new series of live dates:  Go here for all the details.