The Twitterverse was treated to one of the great smackdowns in history yesterday. In response to hip-hop artist Drake's boast that "your first million is the hardest," Texas oil tycoon T. Boone Pickens (who we were elated to learn is a follower of @Drake) had this crippling rejoinder: "The first billion is a helluva lot harder.” Bloomberg Businessweek imagines five other face-offs, using actual quotes from business moguls and rappers ranging from George Soros to Jay-Z.