1 - A 'news' reporter fronting a program on New Zealand's TV3 station dealing with current affairs called 'Campbell Live'.
His reporting style is generally sensationalist and severely biased towards the perceived underdog. He commonly promotes public outrage by feeding the ignorant masses false or exaggerated claims based on pseudoscience. He also supports any minority group he can find, despite the fact that he is the epitome of an upper-middle class metro white guy. This, among other things, makes him a Fag Enabler.
2 - to "do a John Campbell" is to get stuck repeating words like "but" in an annoying squeaky, whingey tone when someone is saying something you don't agree with, especially when the statement you disagree with has something to do with minorities. Named after the aforementioned NZ reporter.
Sam: "I don't like ethnic minorities"
Bernard: (in squeaky voice) "but...., but....., but......, but......, but....., the..... Tangata Whenua......"
Bernard has unwittingly just done a perfect John Campbell.
John Key is the current PM of New Zealand. He was voted in to this position by the New Zealand public solely because he has a slightly more dignified appearance and manner than the previous PM, Comrade Helen.
Although he comes across as a soft, modern man, he recently demonstrated that he is, in fact, a hard man, and is prepared to give all in service of his country. He demonstrated this by breaking his right arm in two places at a function, then carrying on as if nothing happened. He then shook the hands of 120 touch rugby players at another function before seeking medical help. Because of this, the phrase "to do a John Key" now refers to a seemingly uncharacteristic act of bravery and resolve.
Were John Campbell to do something remotely masculine, he could be said to 'have done a John Key'.