"Killing Is My Business... and Business Is Good!" features "Mechanix", a song Mustaine wrote during his time with Metallica. Though Mustaine told the band after his dismissal not to use the music he had written, Metallica recorded a different version of the song, "The Four Horsemen", with a slower tempo and a melodic middle section. The album also included a cover of Nancy Sinatra's "These Boots Are Made for Walkin'," at a faster tempo and with altered lyrics. Megadeth's version generated controversy during the 1990s, when its writer, Lee Hazlewood, called Mustaine's changes "vile and offensive". Under threat of legal action, the song was removed from pressings released from 1995 to 2001.