"Rock Hard" is a single by the Beastie Boys, released by Def Jam Records on 12" in 1984. The track contains samples from the AC/DC song "Back in Black", which was used without obtaining legal permission, causing the record to be withdrawn. When the group planned to include the out-of-print song on their 1999 compilation, Beastie Boys Anthology: The Sounds of Science, AC/DC refused to clear the sample. Mike D spoke to AC/DC's Malcolm Young personally on the phone when their lawyers refused to clear the sample, and later said that "AC/DC could not get with the sample concept. They were just like, 'Nothing against you guys, but we just don't endorse sampling.'" Ad-Rock then added, "So we told them that we don't endorse people playing guitars."