Joanna Krupa and her professional partner Derek Hough go one-on-one -- only for ET! The partners have a good time because they make each other laugh, so when ET asks them to interview each other, the good times roll!

When Joanna asks, "What is the best thing about dancing with me?," Derek responds, "Your determination and your good work ethic. But most importantly, you are a really great person. It is like coming to work with one of my buddies. And you make me laugh when you laugh because your laugh is so contagious."

Joanna reveals that her nickname for Derek is goofball, "because that is what you are. You are just a fun goofball."

Derek also shares that the one thing fans may not know about him is that he likes to draw. "My art is all in London," he tells Joanna. "I had to leave it there. I couldn't bring it over and I haven't been back."

When Derek asks if he is too hard on her, Joanna says, "Sometimes you can be hard, but you snap out of it when I remind you I am not professional."

And when it comes to guilty pleasures, Derek jokes, "I can't tell you that." Then he gets more serious, saying, "I don't feel guilty about my pleasure: In-N-Out Burger for sure." And what does he order? "A Double-Double."

Joanna, too, picked food as her guilty pleasure, saying, "Cake. It looks like a soufflé but inside has hot chocolate that melts out with ice cream, whip cream and berries."

Check back on Monday when ET will have a sneak peek of Joanna's upcoming December Playboy spread. Then tune in to "Dancing with the Stars" on Monday at 8 p.m. on ABC for the next competition round.