CM Punk was upset at the fact that Triple H was going to bring in his buddy, Batista, to win the Royal Rumble and then win the title at WM. It got to the point that Vince himself was negotiating directly with CM Punk to bring him back.
That's why a lot of people boo'd Batista when he came in number 28 at the Royal Rumble (hehe...Boo-tista)
But you know what really breaks my heart?