Do you even know what rock music is?

So you are at a party, chatting to some rather lovely member of the opposite sex and getting on rather well. The subject turns to bands and they quite reasonable ask you what kind of music you're into. It's easy, you know exactly what you're into:
"I'm mainly into Rock" you say.
"Rock music? What kind?" Realising the ambiguity of your statement you mentally kick yourself and start to explain. But something is wrong - your mind goes blank, genres slip like cupped water from your mind and nameless rockstar faces fly in front of your eyes. You try to name a band and all you can come up with is Coldplay. Coldplay?! You're trying to pull this person! You begin to sweat as your target's attention wanes, and they begin to wonder whether you like music at all. You LOVE music, your a fanatic, an expert, a die hard and still, you realise, you have absolutely no idea what Rock music is.
It is impossible, it seems, to describe fully the nature of rock music. Even Wikipedia is a let down in this area. Rock has been through so many stages, fractured in so many places and in many cases diluted into an entirely different form. What was originally a counter culture or an anti-establishment statement has recently become used as a mass market tool and as such has changed the image of the genre. I could write an essay about the sell-outs, the copycats and the money guzzling industry types but the real upshot is that it leaves thousands of guys stranded helpless, wordless and shagless at parties the world over. Don't be one of them - read your trusty music blogs and be equipped for when Fern Cotton asks you what bands you're into...Mmmm Fern.