Great minds think alike. Before MF DOOM and fellow producer and rapper Madlib were canonized as heroes of hip-hop’s underground scene, they were two oddballs who’d amassed cult followings for the ways in which they colored outside the lines. Both had an affinity for Melvin Van Peebles samples, and both had maintained a variety of bizarre alter egos: Madlib had done time as the high-pitched Lord Quas, among others, while DOOM’s nom de plumes included King Ghidra/Geedorah and Viktor Vaughn. Introduced by a mutual friend, the bicoastal pair became fast friends and collaborators, creating a side project, Madvillain, that led to 2004’s Madvillainy, a one-off album that was decidedly to the left of what hip-hop fans were hearing on early-2000s commercial radio, with songs that defied formulaic pop song structure. In fact, the 22 tracks collected on Madvillainy are more like sound collages with lyrics. There’s a celebration of cannabis (“America’s Most Blunted”), as well as an ode to spaced-out jazz legend Sun Ra (“Shadows of Tomorrow”). The duo could be silly, as with “Operation Lifesaver aka Mint Test”—on which DOOM ponders the paradox of an attractive woman with bad breath—or serious, as with “Strange Ways,” a meditation on settler-colonial violence and religion. And their alter egos allowed them to get meta at times: One of the album’s most clever cuts, “Fancy Clown,” finds Viktor Vaughn griping with an unfaithful girlfriend—whom he suspects of cheating with DOOM. While DOOM dazzles with wordplay, concepts, and intricate rhyme schemes on Madvillainy, Madlib delivers with equally fascinating soundscapes. The duo’s unorthodox approach to creativity would inspire everyone from Yasiin Bey to Tyler, The Creator and the Odd Future crew in the years to come, making Madvillainy a watershed album for those willing to take a walk on the weird side.