"Smells Like Teen Spirit" was the #1 song on this list for 23 years — more than half my lifetime, and more than the full lifetime of many of this site's visitors.  So for those who weren't 17 in 1991, let me take a moment to discuss the resonance of this song's key line.

"Here we are now":  In the '80s, being a member of what would come to be called Generation X meant being ignored.  Most immediately, it meant being ignored by our invariably divorced parents; we carried latchkeys and spent hours alone in our houses.  More broadly, it meant being ignored by popular culture, on which the Baby Boomers had a strangehold that seemed unlikely to ever end.  In the '60s the focus had been on those kids who were out there changing the world and didn't trust anyone over 30; in the '80s, it was on those now-over-30s and their nostalgia for their vanished youth.  Even worse than the endless '60s nostalgia was the fact that it seemed warranted.  Who could ever be nostalgic about the retrogressive and stultifying '80s?  Even the best '80s music was a guilty pleasure, fun but overproduced and synthetic; by the time my peers and I got to high school, our taste had developed enough that we listened to the bands our parents had listened to — the Beatles, the Doors, Pink Floyd — and reluctantly accepted that there would never be a band in our lifetimes to surpass the ones that had come and in many cases gone before we were born.  Then came "Smells Like Teen Spirit".

"Entertain us":  When we weren't ignored, we were dismissed as unworthy.  Young people had once protested unjust wars and marched for civil rights, we were told, but our apathetic generation just watched MTV and played video games.  And when the people who broke you sneer at you for being broken, when they congratulate themselves for being better than you even as the world they've made is in obvious decline, and you're too young to have the power to stop any of it, what can you do but learn to find it all darkly absurd, to roll your eyes at everything?  We learned to speak entirely in sarcasm, to hide our fury and hurt under layers of irony.  And "Smells Like Teen Spirit" spoke our language.  The basic premise is hilarious:  So you think we deserve to be ignored because we couldn't possibly have anything to say but "entertain us"?  Great point!  Here's our generational anthem, and that is indeed what it says!  Oh, and one more thing: while we were making an anthem out of your mockery of us, we figured we might as well make it the best anthem ever written.  Enjoy!

All that said — the lyrics of songs are generally irrelevant.  In this case particularly so, since no one could actually make them out.  (At one point MTV resorted to subtitles.)  What turned "Smells Like Teen Spirit" into a massive hit, what made people pay attention long enough to hear the key line, was that sound.  It signaled that the hair metal and button music of the '80s were over, that '90s music was going to be its own thing, and it would be better than anything that had come before, and it would be ours.  Because for about eight million of us, this was the first song to come on the radio that sounded like the inside of our heads.