We've examined the most talked about drugs in hip-hop and the rappers who were talking about them the most, and now Project Know has applied the same to rock 'n' roll. Digging through the lyrics of 15,000 songs, alcohol was easily the most discussed substance, followed by weed and cocaine. Separated into the five categories of alcohol, cocaine/crack, meth, prescription painkillers and weed, Tom Waits not only leads in mentions of alcohol, but also leads other artists with over 60 songs mentioning drugs or alcohol, followed by Grateful Dead and Bob Dylan with both over 30 songs each.