Most rational thinkers agree old people should not educate the young, they should just entertain them.
Grandfathers reluctantly come to this realisation just before their teeth start falling out.
It is one of life's most chilling moments for them.
My teeth are utterly sound, but the fact I am now merely an entertainer to little children is, sadly, sweeping over me like a restaurant waiter's jug of spilled sauce.
A few weeks ago, I was brought to my knees by the minute Jude (6), and as a result, I am distinctly uneasy about ever communicating with him intellectually again.
Dinner had just ceased, and as usual I ran a huge bubble bath to get out of cleaning up.
It must be said also the area around the sink and dishwasher is ridiculously congested and for me to keep out of the way was thoughtful and very kind.
When I had sunk deep into the bubbles and was in a state of zen only the tuatara would understand, Jude came in and surveyed my contented zenith.
''Why do you have so many bubbles?'' he asked.
''These are not bubbles, Big Guy,'' I replied I call him Big Guy because he is 11 inches tall, even though he eats like a bison.
''This is ice-cream flavoured candy floss. Would you like to try some?''
''They are bubbles, granddad,'' he said.
''No, no, no,'' I protested.
''Candy floss! Tastes like ice-cream!''
To prove this absurd claim, I mashed a fistful of bubbles into my mouth and shouted ''YUM!!''
Jude had not long beaten me twice at Yahtzee, so he was on something of a roll.
''It is a bubble bath, granddad,'' he said.
And walked out of the room.
I lay there for a while, no longer in zen, and resolved to speak more intelligently in the future.
The little fella was growing up fast. It was vital our conversations became a battle of wits, not a battle between a twit and a wit.
Futsal was sweeping over our lives like a huge sweeping thing.
Rowan (9) was an instant star, recalling Zidane and Messi as he tore up and down the Edgar Stadium courts, also the only one in the team who actually sought to head the ball, as well as possessing a deft lofted pass over defenders' heads where his team-mates merely drilled the ball hard into every pair of legs they could find.
Jude, a terror when playing at home, breaking a hall window at his own house and thrashing our 38-year-old son regularly when playing away, was a much quieter presence at the stadium.
He moved beautifully into space and always looked to pass, but seemed reluctant to play with the Rottweiler fire of his older brother.
Mind you, Jude was in a strange team, a strange, unbeaten team what's more: in their opening game of the season, one of their players scored six goals, three for each team.
I am not making this up, the boy had excellent ball skills, and when he saw a relatively undefended goal, inevitably more often his own than the one at the other end of the court, he just steamed towards our incredulous goalkeeper and thundered the ball into the back of the net.
Even a few games into the season he was still doing this, leading to the coach calling out one of the most memorable coaching calls I have heard in six decades of watching childrens' sport - ''Wrong way, mate!''
But last Wednesday, semifinal day, the Fleetwood Mac concert turning city traffic into chaos, only half of Rowan and Jude's teams made it to the stadium on time.
Both decimated George Street Normal teams lost.
I resolved to lighten Jude's despair, even though he didn't have despair, only I was despaired, and restart high level intellectual discussion, by showing him my new Sally Army-acquired Beatles slippers, and leading that into a discussion on intellectual property and branding in the modern marketplace.
''Look at these, Big Guy,'' I said.
''Beatles slippers. I bet one of The Beatles wore them.''
Jude knows The Beatles.
''Rubbish, granddad,'' he said. And walked out of the room.
• Roy Colbert is a Dunedin writer.
