I guess it's time for you to hate me again...

What the fuck is up with Eminem's last album (and a half; Relapse + Refill) having all sorts of "ball" references? He doesn't do anything without a distinct purpose, so I can't help but assume the three thematically similar songs in the past year are somehow related. I just don't know what "ball" refers to. I'm hopelessly behind in lingo, or whatever.