(Photo: Robert Bejil)
What gets your heart pumping and your head banging? It's definitely not lyrics that include words such as "committee" and "approximately."
Iain, a data scientist, blogs at Degenerate State. He conducted a statistical study that determined which words are most and least likely to be associated with heavy metal music. You can see his computational methods and detailed results here.
-via Ace of Spades HQ
Metal words = 'rock', 'fire' , 'yeah'
Non-metal words = 'anniversary', 'photosynthesis', 'syllable'
The same rule applies to rap.