B.Y.O.B. (Bring Your Own Bombs) is a song by American heavy metal band System of a Down. It was released in March 2005 as the lead single from their fourth album Mezmerize. Like their earlier song Boom!, it was written in protest against the Iraq War. The song reached number 27 on the US Billboard Hot 100, the bands only top 40 hit.

Directed by Jake Nava, the music video for B.Y.O.B. shows an army of soldiers marching through the streets, wearing paintball masks with television screens projecting words like (Die), (Truth), (Obey), or (Buy). The band members are playing in the middle of the street. During the chorus, the band is shown playing inside a night club. Midway through the video, co-lead vocalist Daron Malakian is screaming the lyrics when the soldiers storm the night club and force everyone to put on the masks, during which the masks show images of television shows and war. At the end of the video, the band members are shown wearing the masks which are displaying static.

B.Y.O.B. originally means (Bring your own Beverage) in party terms, but in this song it is supposed to mean (Bring your own Bombs). And when they say (party) they mean war.

This song is not about partying at all, because if you read the lyrics it is obvious.

Generally, it is just an anti-war song. Also, it is about how they send the poor into war.