One thing that I like to do is use words that have never actually been used in a rap song before. I also like to take words that have negative connotations and show their real meaning.
Darla [from Buffy The Vampire Slayer] was where I grew up. For me, Darla was like going to graduate school for acting. I learned so much with Joss Whedon and David Greenwalt. They encouraged us to make creative choices with our characters.