"O.P.P." is a song by American rap group Naughty by Nature. It was released in August 1991 as the lead single from their self-titled debut album Naughty by Nature. The song was one of the first rap songs to become a pop hit when it reached number 6 in the U.S. and number 35 in the UK in 1991. Its declaration, "Down Wit' OPP" was a popular catchphrase in the U.S. in the early 1990s. It was a hugely successful single, as Allmusic described: "There was not a bigger, more contagious crossover radio smash in the autumn of 1991 than Naughty by Nature's ‘O.P.P.'"
In 1998 the song was named one of the 100 best rap singles by The Source.
In 2008, it was ranked 22 on VH1's 100 Greatest Songs of Hip Hop. It also appeared as number 53 on VH1's 100 Greatest Songs of the '90s.