Monster Magnet has a line in one of their songs, "Bummer," that basically sums up the entire genre of stoner rock:
It's against my second natureAlthough it's not quite the same without Dave Wyndorf's derisive "HAW HAW HAW HAW" after it.
Not to chase you down that hole
I need a fistful of medication
Just to keep it in my pants
What other lyrics so succinctly sum up their genre? There's got to be a bunch, but I'm having trouble thinking of them. For the blues, it's probably hard to beat this gem from Willie Dixon's "Third Degree":
Got me 'cused of taxesDixon, of course, wrote a great deal of Muddy Waters' repertoire, and had his songs ripped off by Led Zeppelin. If anyone represents the genre, it's him.
I ain't got a dime
Got me 'cused of children
And ain't nary one of 'em mine
Bad luck is killin' me
Anything coming to mind for anything else? It seems to me like it's harder to do the less codified the subject matter for a given genre--blues has a pretty straightforward thematic set, so it's far easier. Hip-hop, metal, and country are probably likewise simpler to find (and subgenres like stoner rock or nerdcore are even easier). But what to do for something like indie, or jazz?
Trivia experiments like this always make me want to try to write something that goes way outside of the standard definitions for a genre's subject matter. A nerdcore blues song, for example, would be a fun thing to attempt.