The art of the celebrity interview is a subtle one. You want to let the celeb promote whatever movie it is they're there in connection to, plus have a nice little chat where you become best friends forever by the end.

When Will Ferrell came to chat with Conan O'Brien on "Conan," however, he was very clear about his rules: he most definitely did not want to chat about Professor Don Feathers, the white cockatoo perched on his shoulder and back throughout the interview.

"I'm happy to come on your show, I'm happy to talk about the movie, 'Get Hard,' I'm happy to talk about, you know, anything," Ferrell said. "But I don't want to talk about my personal life, OK? So we're not going to discuss the bird on my shoulder, OK?"

And you know what happens when you ask about Professor Feathers when all Professor Feathers wants to do is hang out and chill? Professor Feathers gets pissed.

Watch what happens below.