Try as the memory wheelie bin might, some nightmarish visions from childhood just refuse to disappear.
Pressed down as far as the subliminal mallet can hammer, they periodically rise up out of nowhere and chill the central nervous system to its spine.
Such it was last week when I was ambling south along Princes St without a care in the world and suddenly, growling from the frontage of an antique furniture store, were two wooden jumping vaulting horse things which threw me back into the black horror of the Otago Boys' High School phys ed gymnasium in 1964.
What exactly are these things called?
They certainly aren't called wooden jumping vaulting horse things.
Google Images was no help - the long rectangular boxes were there, but where were these four-legged slightly pyramidical school gym torture toys?
I am sure they were called horses, but no horse this shape is ever going to win a race, I can tell you that right now.
I enjoyed sport at school.
Ball games mainly, but long distance runs, which nearly killed the fat boys and had their mothers squawking with absence notes the week after, please don't make my boy run ever again he's delicate, were fun too.
But somebody who didn't like sport made up the physical education syllabus in those days, a somebody whose children would later make up the syllabus for Guantanamo Bay.
Not just vaults, but ropes, 6m up to the ceiling with a cane-wielding PE teacher snarling at the base.
This was physical education in the 1960s. Hopefully, it has died out since, like military training, although Mrs Parata has that look about her she will bring it back.
For teachers.
I can look anyone who asks squarely in the eye and say I never once managed to vault over one of these wooden jumping vaulting horse things.
There were kids even in my primary school class who would soar over these things when the notch raising the movable square bit on top was 4 or 5.
While athletic midgets all around me would calculate their run-up to reach maximum speed upon elevation, I would calculate my run so I would slow down more and more until when I reached the wooden jumping vaulting horse thing, I had ground to a complete halt.
''C'mon Colbert!'' the PE teacher would implore.
''Surely you can get over.''
''Sorry sir,'' I would reply.
''There's just nothing left in the tank.''
The other kids would laugh unmercifully, almost as if I was an unco-ordinated gutless weakling with the courage of a raisin.
None of them knew I was good at real sport, that I once took five wickets in five balls against St Edmunds in a Saturday morning junior cricket game, or, later, would briefly get down to a 16 handicap at golf.
I mean, what possible use in life is the ability to soar over a wooden jumping vaulting horse thing?
Jackie Chan, yes, maybe he was reared this way. And he's rich. But nobody else. Education is designed for life.
Never once in life have I needed to soar over someone or something with legs spread wide.
Maybe lift-off made the wrists slightly stronger, but heck, there are other things a teenage boy does with his wrist to make them MUCH stronger, without the threat of smashing both kneecaps and breaking both ankles.
The legs might learn how to splay in mid-air, OK, but you put that skill on your CV and you will be thrown out of the interview room in a heartbeat.
Ballet is the better teacher.
The two wooden jumping vaulting horse things outside the antique furniture shop were still there the next day, strangely un-initialled or blood-stained, unlike most wood at Otago Boys' High in the '60s.
I could still sense the pain and anguish within their cruel and ugly lines.
They were inexplicably chained together, as if someone would steal one but not two.
I contemplated returning with an axe and a sign reading Free Firewood, but that would have been infantile.
Childhood nightmarish visions are best left alone.
• Roy Colbert is a Dunedin writer.