Once a year, XXL magazine crowns 10 up-and-coming rappers they think are going to take it to the next level as "Freshman." But this shared experience in the cover-world limelight doesn't mean that things are all good between the alumni. For example, Class of 2013 freshman Joey Bada$$ took aim at 2010 graduate Big Sean after Sean released a promo to his Hall of Fame album called "Control" that virtually shut down the Twittersphere. The song featured verses from Jay Electronica and Kendrick Lamar. Joey's response? "Big sean verse was weak. Sorry," he tweeted. This is definitely not the first time XXL Freshman rappers have fired shots at each other, though. Click on for more cases of class warfare.