"B.Y.O.B." ("Bring Your Own Bombs") is the first single released from Armenian-American alternative metal band System of a Down's fourth album Mezmerize. Like their earlier song "Boom!", it was written in protest against the Iraq War.B.Y.O.B. means "Bring Your Own Bombs", as opposed to the common interpretation "Bring Your Own Booze", referring to the Iraq War as a party for the United States. It is also a playable track in the music video games Guitar Hero World Tour, Guitar Hero Live and a downloadable track in Rocksmith 2014.

The video for "B.Y.O.B." was directed by Jake Nava.

The music video shows an army of soldiers marching through the streets, wearing paintball masks with television screens projecting words like "DIE", "TRUTH", "OBEY", "BUY" or "GOD", with the members of System of a Down playing in the middle of the street. During the chorus, the band is shown playing inside a night club. Midway through the video, Daron is shown screaming the words "Blast off! It's party time! And we don't live in a fascist nation! Blast off! It's party time! And where the fuck are you?!", when the soldiers storm the night club and force everyone to put on the drone masks, during which the masks show images of television shows and war. At the end of the video, the members of System of a Down are shown wearing the drone masks, which are playing static.

The music video was censored for air-play reasons.

The song itself was featured in the fourth installment of the Guitar Hero series in 2008, Guitar Hero World Tour. It is regarded as one of the most difficult songs to be performed in vocals, predominantly due to the recurrent screams of Daron Malakian, as well as in both drums and guitar. It is also the hardest song in the game to play for the bass and for the band as a whole (2 or more instruments), as it is feature as the final encore for the bass and band careers.

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