Rockhold alluded to Werdum's ass-scooting loss to Overeem in Strikeforce when he was explaining why he doesn't like him.
Whatever the beef is, it goes back some time.
Greg Savage told the story on Cheap Seats that back in the day, before Rockhold had even won the Strikeforce title, after an event he was jumping into his limo with a girl he had picked up when Werdum's BJJ coach jumped in and pretty much stole his girl out from under him.
They were on the way to a strip club anyway, so, he brushed it off and met Savage and Breen outside the club. This club only had one unisex bathroom, just one of those single toilet and sink in a closet deals, and there was a que for the toilet. Later in the night they, being Breen, Rockhold, and Savage, are queing for the toilet, when Werdum, his BJJ coach, and the girl he stole from Rockhold come breezing along and skip the whole que.
Werdum goes straight in the toilet, but Rockhold starts kicking off with the BJJ coach, the BJJ coach is telling Savage you best control your boy or he is going to get his arse kicked, and Rockholds pretty much ready to throw down. Werdum comes out of the toilet into this mess, and things start looking like its going down right then and there.
Savage is contemplating just throwing on the BJJ coach and trying to get the early knockout, because he figures if that doesn't work his fat arse is fucked, and he will soon be choked out, or worse. And just when this is going down, Hendo and some others come along, and Hendo manages to cool Rockhold down and nothing comes of it in the end. However, later in the night, or perhaps soon after, as they are leaving Rockhold is still saying I can't believe I'm not beating that guys head in, I should be kicking his arse right now, and things to that nature.
From the way Greg tells it, Rockhold has never forgotten that night, and it has started a long running feud between Werdum and Rockhold. Greg tells it better, this is purely from memory and any mistakes are my own, it's worth a listen to this weeks cheap seats just for this story. Sorry, I can't tell you what minute it starts though.
Cheap Seats: UFC 195 Review, Year-End Predictions - MMA Radio - Sherdog.com