I used to have a good little system for bunking off sports in school. I knew how long to wait so I could sign in, where to go to escape without being seen and how to time it to make sure my parents wouldn't be home if anyone from the school tried to call. It was relatively well constructed but, of course, it eventually fell apart.
I learned an important lesson back then: you'll never get away with it forever. Unless you plan very carefully, you'll usually get caught out.
Alex Salmond is currently discovering this lesson on a rather bigger stage. For years he has been making it up as he goes along. But suddenly he is being found out. Chancellor George Osborne has ruled out currency union and European Commissioner president Jose Manuel Barroso has said it would be "extremely difficult if not impossible" for an independent Scotland to join the EU.
This one-two punch, on the SNP's electoral and emotional sweet-spots, poses an existential threat for Salmond's campaign for Scottish independence. It is like the harsh light of sobriety on the mind of an alcoholic. It's the first moment political facts have intervened in Salmond's lazy, irresponsible imagination.
Stare deep into Salmond's career and the most telling element is that of absence. Aside from independence, he appears to have no political conviction whatsoever.
It is there in the foundations of his current political mission. When asked to adopt the leadership of the SNP following the resignation of John Swinney in 2004, Salmond quoted union army general William Sherman, who, on being asked to run for president following the American Civil War, declared: "If nominated I'll decline. If drafted I'll defer. And if elected I'll resign."
But everything changed shortly afterwards, when he found himself entering the leadership race "with a degree of surprise and humility, but with a renewed determination". He has the consistency of a flag on a windy day.
Even his personality seemed to change, from bitter aggression to beaming, cheeky bon-homie.
His politics are the same: indistinct and liable to change colour. Take a step towards them and they take one step further away.
His influence was established by his membership of the '79 Group, a socialist campaign within the SNP. A few years later he was praising himself for having "given the SNP a social democratic identity". But even that drift to more centrist politics did not tell the whole story.
For all his professed commitment to social democracy and a generous welfare state, Salmond reveals more by his friendships than his words.
The Leveson Inquiry revealed how Salmond and Rupert Murdoch exchanged admiring letters and held private dinner dates. He held more than two dozen meetings with the press baron or his executives. In its final report, the inquiry said: "Mr Salmond’s readiness... to stand ready to assist News Corp is striking". Salmond's desire to lobby for the BSkyB deal "would have rendered the decision unlawful" if it had taken place.
When the time came for Salmond's left-wing credentials to be tested, he put the needs of rich American right-wingers over those of local people. Donald Trump took time out from trying to prove Barack Obama is not American to demand an obscene golf complex for the super rich in Scotland. It was "called in" by Salmond, despite the objections of local planners, environmentalists and local people. The plans were eventually pulled following a legal dispute.
His lack of conviction isn't just a matter of ideology. It fundamentally affects his judgement on the constitutional issues raised by independence. Simply put: there is no political idea so insignificant Salmond will not have developed more than one position on it.
His U-turns are as numerous as they are weighty. He was for the euro and then against the euro. He branded sterling a "millstone around Scotland's neck" and then decided he wanted it. He thought Iceland, Ireland, Norway, Finland and Denmark could form an "arc of prosperity in the northern rim of Europe, in a speech which showed he was unaware of the differences between high-tax-and-spend Scandinavian economies and low-tax economies like Ireland. He was later to change his mind when Iceland and Ireland fell apart in the wake of the financial crisis.
He was against Nato. And then he was for Nato. He said he had seen the legal advice on EU membership. And then it emerged it did not exist.
When president of the European Council Herman Van Rompuy finally did state the position, it was clear that Scotland would have to go through the full accession process to join the EU. He also rejected Salmond's imaginary notion that Scottish membership could be finalised while it was still part of the UK.
It doesn't matter what anyone says. The SNP just keep spewing forth the same myths and bedtime stories. Deputy first minister Nicola Sturgeon was insisting today that Scottish membership could be finalised in 18 months. She's like a wind-up toy in an empty room.
Salmond is a chancer. When you look into his politics, you find nothing but air. He comments first and only afterwards bothers to check if what he said was true. As his biographer David Torrance noted: "As in so many other areas, the SNP only thought seriously about the ramifications of retaining sterling having already announced it."
Now he has been caught out on the two biggest issues imaginable: currency and EU membership.
His response is to brand Osborne a fellow chancer – a man bluffing before pulling a volte-face after the referendum. Osborne is many things, almost all of them bad, but on this issue he is not unwise.
Why would Britain enter into currency union so it can shackle itself to an independent state but still have to bail it out if things go pear shaped – a not unrealistic scenario given Salmond's judgement?
And why would Scotland want independence just so it can be economically controlled by London but without any representation? What kind of independence is that?
Why would the EU allow Scotland membership in a manner which is not consistent with rules for other states? What would happen to Scottish citizens in Europe if Scotland, as seems almost inevitable, had its EU membership cancelled, even if temporarily?
Salmond's response to these weighty issues has been to slander and obfuscate. He branded Barroso's comments "preposterous" and "nonsense". This is the European Commissioner president - not some talking head commentator on Sky News. He cannot be written off with Salmond's colourful bluster.
His currency union argument is entirely emotional. He seeks to play to the gallery with the meaningless statement that "the pound is as much Scotland's as the rest of the UK". It is pure fairy tale politics.
Here is the simple fact about Alex Salmond: he's making it up as he goes along.
His absence of consistent political beliefs is merely a character deficiency. But his wilful disinterest in the issues which will affect the lives of his fellow countrymen is a substantial failure of political responsibility.
Ian Dunt is editor of Politics.co.uk
The opinions in Politics.co.uk's Comment and Analysis section are those of the author and are no reflection of the views of the website or its owners.