A few years ago, we were watching TV at work and one of those "100 Greatest Whatever" shows was playing on VH-1. This particular one was devoted to "hard rock", and they naturally applied a liberal definition of that term. After all, they have a lot of time to fill!
Anyway, my co-workers were rather enjoying the program - that is, until the Sex Pistols showed up. My hapless work buddies wrinkled their noses and complained at how terrible a band they were. All I could do was laugh. Most of these people hadn't even been born when the Sex Pistols were breaking new ground for rock 'n' roll hooligans.
Thirty plus years later, the Sex Pistols still have the power to enrage and disgust. That is the definition of punk.