There is only one kind of coup in politics: the one that actually works. However, there are numerous varieties of attempted coups.
At one end of the spectrum is the kamikaze, in which the challenger swoops in and fires, only to crash and burn. Then there is the silent but violent coup, the variety David Cunliffe tried at the Labour Party's conference last year. That involved simply refusing to rule out challenging for the leadership or to express confidence in the leader, who was and remains David Shearer. It is intended to buy time to assess whether the support is there while leaving wriggle room for the coupster to claim they never actually challenged for the job and the body language was simply misinterpreted.
Just below that is the turtle coup. The turtle pops its head out of its shell, realises it is still winter and pops its head straight back in again to await spring. Lowest on the rankings is the imaginary coup.
People had different theories about which of the last two types of coup attempt was under way, or not under way, in Labour this week.
It began with a single tweet from RadioLive's Duncan Garner, a former political editor for TV3, which stated a good source had told him a letter of no confidence in Shearer was doing the rounds. Alas for Garner and his source, nobody else had seen this letter.
There were theories as to whether either the source or Garner had misinterpreted some innocuous event. One was that David Cunliffe had texted to tell someone dinner was almost ready, but autocorrect resulted in "the coup is on" instead of "the soup is on". Another was that there were so many signatures doing the rounds this week that it became hard to tell who had signed what.
First there was United Future's presentation of 500 members' signatures to the Electoral Commission, then the asset sales petition organisers presented 51,000 more signatures in their second bid to force a citizens-initiated referendum on asset sales. With such a tsunami of signatures, who could blame Labour for trying to slip through the mere 18 signatures needed to force a referendum on the leadership in their own party?
Labour MPs reacted in anger to reports based on unsubstantiated rumour. An indignant Annette King chose to retort with a bit of satire, ringing up to say that since uncorroborated sources were now so credible, "I have a source, too, and my source has told me that a minister has a close association with a goat".
Pushed further, she said she had no knowledge of which minister, or what type of association said minister might have with a goat. Whatever it was, surely it must be true if "a source" had reported it.
For Shearer, whether fairly or unfairly, everything is seen as "a test of his leadership". The Ikaroa-Rawhiti byelection was a "test of his leadership". The man-ban, too, was "a test of his leadership", albeit one he could never pass. Shearer was first of all criticised for allowing the man-ban to pop up at all, then for taking a full three days to squash it out of existence while simultaneously being criticised for doing that rather than allowing matters to take their democratic course and go to the party's AGM for the members to decide on. In reality, his other MPs didn't like it much more than he did so it was unlikely to have sparked a revolt. Nonetheless, the timing of Shearer forcing a retreat on women-only selections added fuel to the coup rumours.
So, too, the coup rumour itself was a "test of his leadership". With actual coup attempts, there are only two results. Either it is successful and the defeated incumbent is left to put his belongings in a box and leave. Or it is not, and the triumphant incumbent can prove he or she is a strong leader by putting the challenger back in their box. Unfortunately, as Julia Gillard learned, sometimes that only creates a Jack-in-the-box which pops out again without warning.
This time round, the rumour was so vague that nobody seemed to know who Shearer was supposed to be putting back in the box. Was it Andrew Little or Shane Jones? Was it Cunliffe, getting a last-ditch bid in before his supporter numbers diminished even further with the departure of Lianne Dalziel so soon after Charles Chauvel? Was it Grant Robertson? Did Clayton Cosgrove have anything to do with it? Where was Wally?
It was like Heracles wrestling the Hydra. One of the problems is that imaginary coups are more dangerous than the real thing and as tricky to handle as Winston Peters in a coalition. There are only two tactics to try to rebut the rumour: deny or ignore. Both are equally useless. Nobody believes denials but ignoring it only fuels the rumour because there is no denial.
That such a tip was believable from the get-go should not surprise Shearer, but it should worry him. Labour has just implemented a lengthy electoral college process for electing its leader so it is probably safe to assume that a turtle coup attempt is in gestation. Labour MPs are surely at least working out the red tape needed to mount a coup under the party's new rules should the day come when it is needed.
The real danger of even imaginary coups is that they have the tendency to turn into self-fulfilling prophecies. Sure enough, by the next day there was a school of thought that Garner's tip-off had not been wrong at all - simply prescient - and that hidden away in an MP's desk lay a little piece of paper awaiting the signatures of those 18 members of Parliament.
It is, as blogger Danyl McLauchlan observed, a bit like weather forecasters predicting it will be cold in winter.