Rapping is very meta. A lot of rapping is about how good you are at rapping. Or about how successful and wealthy you are--thanks to being good at rapping.
Sometimes you think rappers might be rapping about something other than rapping, like The Genius here in "Liquid Swords":
I'm on a mission that niggas say is impossible,
But when I swing my swords they all choppable.
I be the body dropper, the heartbeat stopper,
Child educator plus head amputator.
But it's all just a metaphor for rapping. The next lines in the verse:
Cause niggas' styles are old like Mark 5 sneakers.
Lyrics are weak, like clock radio speakers.
GZA amputates your head lyrically. The "s" in "swords" is merely stylistic.
When rap is completely meta, just a pure feedback loop devoid of any story or lesson, the fun lies in the rapper's creative flourishes, the ornamentation on the perpetual motion machine. There are uncountable ways to say "I'm good (at saying I'm good (at saying I'm good (at saying...)))"
But even given rap's overwhelming self-referentiality, I was struck recently when I re-listened to the R&B song "Feels Good" by Tony! Toni! Toné!.
Here are the lyrics to the rap interlude.
Mosadies the Mellow, quite a nice fellow.
Met three T, hit a rhyme acapello.
They had the rhythm and I had the rhyme,
So then I hit it that one more time.
It worked out and then they worked it in.
Tony Toni Tone has done it again!
As you can see, nearly the entire rap (five of the six lines) is about the arrangement and recording of the rap. Explicitly. No fancy (s)wordplay of note. (Unless you count "it worked out" as brag-worthy braggadocio.) What I'm saying is, I think this might be the most pointless rap interlude ever.
Any other contenders?

Is that dope enough indeed I paid the price to control the dice!
I'm more precise to the point I'm nice !
Let the music take control of your heart and soul!
Posted by: Glen | August 10, 2011 at 12:13 AM
Here from Andrew Gelman! I guess because rap is competitive, rapping about how good you are at rapping is actually "taking the high road" - because otherwise you'd be doing an attack ad against your specific opponent aha.
Also, it's fun to compare this with Kpop (Korean pop) where even the girl idol groups have a "rapper" and the rap is just used as a bridge in the song, and is generally about whatever the rest of the song is about. http://www.youtube.com/watch?v=bVM-LaB0tI4
Posted by: Sub-divided | January 19, 2012 at 03:35 PM