'straight-edge refers to a philosophy that's most basic tenets promote a drug free lifestyle. It developed as an offshoot of the punk rock/hardcore scenes of the early 1980's when the term itself is believed to have been coined by Ian Mackaye, in the self titled song, while he was the singer of the seminal hardcore band, Minor Threat. Mackaye eschewed the nihilistic tendencies of punk rock, promoting instead the simple (almost simplistic) philosophy of "don't drink/ don't smoke/ don't ****." '

That's the definition of it I found. I guess it works just like religion, it all has its hypocrites. So, you condone the ****ing but God forbid someone smokes. Wow, that makes no sense at all.