Credit: Barry Brecheisen/WireImage

Gnarls Barkley’s 2006 smash “Crazy” — that pulsating slice of retro R&B for the digital age — clocks in at just over three minutes, but it still captivates and inspires a decade later. Not that CeeLo Green and Danger Mouse expected that the song, which celebrates its 10th birthday today, would have that type of longevity.

“I didn’t think much of it at the time,” CeeLo tells EW. “This is not to devalue it — I just didn’t know.”

Considering the song’s success, that might seem, ahem, crazy. But the singer has a point. While CeeLo had gained notoriety in the ’90s as a member of the hip-hop group Goodie Mob, he hadn’t yet had a smash hit of his own. Brian Burton, who produces as Danger Mouse, would later leave an indelible mark on alternative music through his work with Beck, the Black Keys, and Broken Bells, but when he convened with CeeLo in 2005 to record Gnarls’ debut, he was best known as the guy who’d mashed up The Beatles’ White Album with Jay Z’s Black Album.

Those relatively humble roots defined the week of Atlanta sessions that produced “Crazy” and St. Elsewhere. “They’re very simple songs the way that they were done,” CeeLo says. “They aren’t pretentious at all.” Danger Mouse came armed with an arsenal of brief instrumentals, which he’d bounce off CeeLo: “He felt that if he could hold my attention for two minutes, then maybe there was something there. I felt compelled with the task of seeing how poignant, how effective I could be in this short amount of time.”

“Crazy” was just another of the batch. When Danger Mouse played the beat for CeeLo, he loved it so much that he says they put it on loop in the studio for nearly six hours. That immersive experience soundtracked the conversation that led to the song’s iconic lyrics.

“We talked about rock stars and authenticity,” CeeLo says. “Why it is that someone has to be crazy — or the thin line between being crazy and being totally convinced of something. We were talking about the Ozzy Osbournes, the Iggy Pops of the world, the Jim Morrisons. We reveled in those individuals, those icons. … We were having this great, nostalgic rock & roll conversation and that’s basically the premise of the song, the sentiment.”

CeeLo says the discussion “just kind of affected the subconscious” and prompted him to jot down the verses and record them in one take. “People just kind of take it as they want to receive it,” CeeLo adds when explaining the song’s vague appeal. “All that we could really guarantee [was] that it had a ring to it.”

And in the same way that CeeLo’s quickly written lyrics became immortalized, so did some of the instrumental quirks on “Crazy.” Those four pulses that kick off the song? Danger Mouse initially added them as cues so CeeLo would know where to start singing. “I just needed that so I could count myself in,” he says with a laugh. “We ended up just leaving it like that. I almost hate to unveil the inner workings of these songs — I love the mystique around these records — but to be totally honest, it was really simple.”

The simplicity resonated. “Crazy” never hit No. 1 on the Billboard Hot 100 — in summer 2006, Nelly Furtado’s Timbaland-produced “Promiscuous” reigned supreme — but it became a cultural touchstone and even inspired other artists to perform their own renditions. “One of the most endearing versions, for me, was to hear Billy Idol do it live,” CeeLo says. “I grew up loving Billy Idol, so to hear him sing my words back to me was an affirmation of arrival.”

And while some artists spurn their biggest hits, CeeLo hasn’t — in fact, he had performed “Crazy” the night before EW connected with him. “I still enjoy it,” he says. “I’m still in awe of it.”