"Rapture" (Blondie)

Back in the late 70s/early 80s, Bronx-based graffiti artist Fred Brathwaite (aka Fab 5 Freddy) was making a name for himself among the SoHo/lower Manhattan gallery crowd, where he also was rubbing elbows with New Wavers and punks.  During one of his early exhibitions, he met Debbie Harry and Chris Stein of Blondie, who ended up buying and commissioning pieces of his art.  The three became fast friends and started hanging out, which is when Harry and Stein began learning about the city's fledgling hip-hop scene and its most prominent figures, like DJ Joseph Saddler (aka Grandmaster Flash). 
Blondie’s 1981 single “Rapture” from the album Autoamerican was inspired in part by Brathwaite taking Harry, Stein, and a number of other New Wavers/punks on a field trip to a 1980 show at the Police Athletic League in The Bronx, where Harry was floored by Saddler's turntable skills.
The other spark that ignited the track was Brathwaite telling Harry that he wanted to make it big, as he recounted in the 1999 documentary The Hip Hop Years by Great Britain’s Channel 4.
“I said, ‘You know, Debbie, I want you to make a record about me.  Or, just mention me on a record.  Because I want to be like a star’.”
He figured she’d never actually drop his name in a song, until he heard the finished single at Harry and Stein’s apartment.  Even then, he was skeptical that they weren’t just playing a joke on him.  After all, Harry wasn't a rapper.  And what New Wave band was going to put out a single with a rap in the middle of it?
It wasn’t until a few months later while hanging out in Paris with Tina Weymouth and Chris Frantz of Talking Heads that Brathwaite heard “Rapture” on the radio (with Harry's rap intact), and he realized Harry and Stein weren’t pulling his leg after all.
As he listened, he also realized that Harry’s odd little rap was chock-full of references to graffiti culture (paint a train), hip-hop (Flash is fast, Flash is cool), and Brathwaite himself--in particular, the lines about the man from Mars, which were a direct reference to him and a rap that he often performed at parties in the early 80s:
I was born and raised on the planet Mars
I used to chill and rock with the stars
Till one day I got bored and decided to split
And I came to earth on a rocket ship
Some sources erroneously cite “Rapture” as the first charting rap song; in actuality, “Rapper’s Delight” (1979) by the Sugar Hill Gang was the first charting rap song (#36 on the Billboard chart).  “Rapture” was, however, the first song containing a rap to go to #1 on the Billboard chart.
(As a side note: Harry had asked Joseph "Grandmaster Flash" Saddler to appear in the video for "Rapture."  When he didn't show for the shoot, she quickly hired rising-star graffiti artist Jean-Michel Basquiat to play the DJ.  You can see Basquiat in the video below, looking kind of lost behind the turntables.)