The ACM Awards last night in Vegas saw some major country cross-over's: Jason Aldean rapped, Rihanna and Sugarland's Jennifer Nettles sang Ri's hit "California King Bed".

But the BEST part of the show was Carrie Underwood and Steven Tyler rockin' the stage!  They killed Carrie's "Undo It" and then went into an amazing performance of "Walk This Way".  I wish I had the same enthusiasm for Carrie's outfit : (