On the surface, this song is about rock stars and how many of them died because of drugs ("Eat all the grass that you want"). The band tells a different story: System Of A Down guitarist Daron Malakian wrote it one night after he accidentally ran over a rabbit. He pulled over the car and named the dead rabbit Rock N' Roll. He felt so bad that he was writing about how the rabbit didn't deserve his fate, so the line "eat all the grass" is referring to the rabbit eating the grass, not rock stars doing drugs.
Matt - Chantilly, VA