I don't know.I think Chrissie is genuine, but Joel is...' playing the game' for screen time with his dancing antics. He has big plans and needs Chrissie to carry them out.
I would be absolutely fascinated if either Big Brother or Celeb had raw statistics of who spends time with whom in minutes.
I think it would be almost impossible to be a pretender in this situation. As people we have many layers. We have a goofy side, a serious side, a fun side, a nasty side, a sneaky side and so on.
One of my favourite things to do is turn song lyrics into creepy porn lyrics, and at times I have been known to make friends/co workers almost pee with laughter. Would I behave in that silly manner towards someone who has just been diagnosed with cancer, probably, so bad example. But I hope you get my point. Our behaviour and response is determined by mood. Unless you drop acid, you don't dance and be goofy 24/7. However if you are that way inclined, spurts of dancing goofiness thoughout your day can be deemed as normal.
I know a man who behaves just like Joel, and I can promise you, the only game he is playing is life.