Picking up the phone, calling Ian Fletcher and suggesting he should apply for the top job at the GCSB, was typical.
He didn't think it through, he just did it.
He decided SkyCity should build the national convention centre in exactly the same way - it was a good deal, so he did it company registration samoa
The SkyCity episode landed him in a heap of trouble, now he's facing opposition attacks on two fronts over Fletcher's appointment as director of the Government Communications Security Bureau.
In both cases he failed to perceive the political consequences of his actions. He behaved like the decisive, deal-making businessman he once was.
That carries great risks. There are opposition MPs lurking in the corridors of power ready to pounce on anything they can use to discredit the government and its leader.
Key didn't break any rules when he called Fletcher.
"It is not wrong or unethical for ministers to suggest people should apply," says State Services Commissioner Iain Rennie.
Rennie admits he was "a little surprised" that Key made the call personally and says there's always the danger of "negative perceptions" arising when ministers directly involve themselves in appointments.
He knows what he's talking about - in 2007 he had to investigate an incident in which David Parker, climate change minister in the previous Labour government, recommended party activist Clare Curran - now an MP - for a consultancy job in the Ministry for the Environment.
She was hired, uncontested, and National went berserk. Ministry chief executive Hugh Logan resigned.
Labour's deputy leader, Grant Robertson, says there's no comparison between that and appointing "the prime minister's mate" as head of the GCSB.
Robertson disputes Rennie's assertion that everything was "absolutely above board" and says Key "fundamentally changed the appointment process" when he called Fletcher.
"He told Ian Fletcher to call Maarten Wevers (then head of DPMC) and Maarten Wevers was on the interview panel which recommended Fletcher for the position," says Robertson.
But however much the opposition protests, the bottom line is that the prime minister appoints the head of the GCSB and Key wanted Fletcher. The appointment process followed state services commission rules and Key is in the clear.
Labour has asked Auditor-General Lyn Provost to investigate the appointment. Whether she decides to do so remains to be seen, but it isn't going to win this one.
It's second front holds more promise.
Key has been less than forthcoming in parliament about his role in the appointment and Labour has laid a breach of privilege complaint with Speaker David Carter.
Robertson calls it "lying by omission" and says Key is guilty of misleading parliament.
Key told parliament on March 27 Fletcher's appointment was made by the state services commissioner cheap furniture stores
Asked whether there had been any further contact with Fletcher since their schooldays together, Key replied: "I can't recall particular occasions, I am sure I may well have done so."
It wasn't until Tuesday this week that Key revealed he had called Fletcher.
Asked why he hadn't mentioned it earlier, he said he hadn't remembered it "at that time".
Labour and Green Party MPs say it's inconceivable Key would have forgotten he called Fletcher, given the intensity of the controversy and the heat that had been generated by daily questions in parliament and from the media.
Given that this is about what Key didn't say in parliament, rather than what he did say, Carter isn't likely to send the prime minister to the privileges committee Claire Hsu
That won't stop opposition parties hounding him over it because they're intent on creating the impression that Key can't be taken at his word.
The prime minister will probably be able to argue his way out of this, but it's going to be messy.