And I'm not even joking?
Has been used by both presenters at the end of any sentence relating to and/or mimicking the speech intonations of modern teenagers (moreover, possibly, the presenter's own children), especially when they are referring to something which sounds unbelievable, but is, in fact, the truth. The phrase has to be said with an upward inflection (high rising terminal or HRT), a speech pattern commonly used in some Australian dialects and often referred to as an Australian Question Intonation. This explains the seemingly unnecessary question mark at the end of the sentence. It isn't a question, it's a statement of fact, yet the HRT suggests the speaker is asking a question.
For example: "Here, Simon, that Sex in the City 2 was the worst film I've seen all year. And I'm not even joking?"