Flipping off the fans, ripping on a major UFC sponsor and adding insult to injury to his challenger Frank Mir, Lesnar certainly did not endear himself to the majority of the 10,673 in attendance at the Mandalay Bay Events Center in Las Vegas.
Lesnar had a behind closed doors talk with UFC president Dana White afterwards and apologized during the post-fight press conference.
"I acted very unprofessionally after the fight," Lesnar said. "And I'll leave it at that. I'm a sore loser, okay? I don't like to get beat. I believe that Frank and I's first bout, I gave that fight to him. So there was a lot of emotion in this fight for me."
Lesnar said his competitiveness and his background in pro wrestling drove him to his over-the-top actions inside the Octagon, which included telling the crowd his intentions to get on top of his wife later in the night.
"You guys ask me all the time: Is there anything I can drag over from the WWE?" Lesnar said. "And I guess you've seen a little bit tonight."
With a bottle of the UFC's official beer sponsor Bud Light in front him, Lesnar added, despite his post-fight actions, that he holds no ill will towards Mir.
"I have nothing against Frank," Lesnar said. "Like I said, the only thing I had against Frank was that he beat me. We both talked a lot of crap and in the end, I was just amped up."