"Saturday" is a single by American rock band Fall Out Boy released from the band's 2003 album Take This to Your Grave. It is still incorporated into the band's set lists and is almost always played last at the group's shows. This is one of two singles by Fall Out Boy to feature bassist Pete Wentz's screams, heard in the background of the final chorus.

The video features all of the band, but particularly frontman Patrick Stump and Pete Wentz. Pete is killing the other band members and their friends, leaving a Queen of Hearts playing card with each of the bodies. Patrick is a detective tracking the "killer". During the bridge of the song, Patrick and Pete are seen in the same position, sitting on a bed with a wall of pictures of Pete's victims in the background, suggesting that Patrick and Pete may be the same person. In the end, Pete kills Patrick, but because Pete and Patrick turn out to be the same person, Pete dies as well.

The video is intertwined with clips of the band playing a show. In the Believers Never Die DVD commentary, the band members said that the moshing and slam dancing were to Hatebreed, not actually Fall Out Boy.

The members of the band have stated that this song is one of their favorites, and typically finish every live show with it; during most live performances Pete Wentz puts down his bass during the breakdown to perform the screaming parts in the final chorus. It is regarded as a fan favorite at concerts. "Saturday" was included as the third track on the band's Believers Never Die – Greatest Hits (2009) album.

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