And finally, this week, Key did just that. He came on to the show and the two Johns went at it.
If Sky TV had this stoush as a pay-per-view they'd have made a fortune.
Key was obviously annoyed at what he believed was misinformation being promulgated by Campbell Live; Campbell was just as cross at the slick answers Key was giving in response to his questions.
Key stayed calm and in control, unlike Helen Clark who lost the plot during the infamous Corngate interview Campbell conducted and that helped him gain the upper hand in the interview.
No matter which side of the fence you're on, it was interesting television.
I think the bill sounds sensible enough - for the GCSB to spy on New Zealanders, they must ask nicely, explain why and then be subject to a review of their investigation.
I couldn't give a fat rat's bum if they monitored my house and my life, but I think it would be stupid to give a government agency unfettered, unmonitored, unlimited access to its citizens. They must be accountable for every decision they make and they must be watched closely.
The bill seems like a reasonable compromise and Key was Mr Reasonable himself when it came to selling the party line and fudging the uncomfortable bits that come with running a spy agency that interacts with others around the world.
Campbell fought his corner valiantly but Key was the clear winner on points.
Debate on this issue is now closed.