The Whiteypedia

This should be good: A crowdsourced project to help people understand rap lyrics. Sort of like Yahoo answers, but for extremely square people. For example:

Top Gun shut down your Firm like Tom Cruise

Term from Song: Woo Ha!!on Album: The Coming by Artist: Busta Rhymes

Busta Rhymes is declaring that he’s the Top Gun (the best) which is the name of a Tom Cruise movie. He will then metaphorically "shut down your firm" (destroy you). The Firm was also a Tom Cruise movie, where he shut down a corrupt law firm.

Even better, if this lyric confuses you: 

better toss that yayo, keep your bankroll

You are in luck:

Term from Song: 1st of Tha Monthon Album: E 1999 Eternal by Artist: Bone Thugs N Harmony