Liz O. Baylen / Los Angeles Times
Along with OutKast's "Hey Ya!" this was quite possibly the most ubiquitous song of the decade. Rapper Cee Lo Green, working with hot producer Danger Mouse, was remade into a soul singer, and the resulting sounds of the single are all over the place.
Lyrically, this is a paranoid freak-out, but also a bit aggressive. Musically, it's vintage, but with plenty of modern touches. Crazy? No doubt, but even more chaotic. If there was a sound to the decade, this was it.