The distinction between daring irreverence and juvenile rudeness – such as in the counting rhyme 'Eeny, Meeny, Miny, Moe' – is usually learnt in the playground.
Kids can say the cruelest things, but in the course of growing up they eventually discover that insults alone don't constitute wit. The joke is always dependent on who is saying it and who they're saying it to.
So, the scrappy kid brave enough to cheek a strict teacher might become a respected class clown, but the popular kids who pick on their lisping classmate aren't brave, they're just bullies.
This appreciation of humour's power dynamic has been summarised in a neat motto used by professional comedians and comedy writers: "Punch up, not down."
It's a principle worth recalling while we're casting our minds back to our own schooldays. Does Jeremy Clarkson's recitation of a racist children's rhyme make him a hilariously waggish idiot? A racist idiot? Or, as his Top Gear co-presenters would have it, just an idiot?
In an outtake dug up by a national newspaper last week, the presenter chooses between two sports cars using a version of Eeny, Meeny, Miny, Moe which includes the line: "Catch a n***** by the toe/If he hollers let him go."
In his later YouTube apology, he defended himself by calling this "the best-known version of the rhyme", but is it? Best-known to whom?
In my schooldays, which probably weren't much like Clarkson's, we used "catch a tiger by his toe", or any number of alternative counting rhymes such as 'Ip, Dip', or 'Tinker, Tailor' that don't include racist slurs.
Presumably, when Clarkson says "best-known" what he means is "best-known to me, Jeremy Clarkson, and the other old white blokes whose world view defines the BBC's reality".
That's okay, though, because Clarkson (below) assures us he "did everything in my power to not use that word". Everything, that is, apart from not using it.
Since there are several alternatives, we can only assume he thought mumbling the racist version might be terribly droll, yet another one in the eye for the PC brigade.
Much like that time he referred to an anonymous Asian man by a racist slur, or described Mexicans as "feckless", or made jokes at the expense of murdered prostitutes, or called for public sector workers to be shot dead "in front of their families".
This time, at least, he thought better of it before broadcast. What a shame the same judgment wasn't exercised on those other occasions.
The N-word has a special power to elicit visceral horror in even the most insensitive blowhards, a power which its history more than justifies.
But while Clarkson shrinks from society's opprobrium regarding this particular unfunny gaffe, his half-arsed apology suggests he still hasn't grasped why his other comments weren't funny either.
Rudeness can be shocking, witty and – if directed at power – even heroic. Coming from a well-paid BBC presenter who regularly sups with the PM, it isn't irreverent. It's just rude.
The National Association of Head Teachers (NAHT) is calling for a strict new charter to prevent children seeing sex and violence on TV before the 9pm watershed.
You might, therefore, deduce that the NAHT wants to protect our innocent children from the harsh realities of adult life. But you'd be wrong.
The same organisation has announced a scheme called Primary Futures, which invites professionals to explain to children as young as five "the practical requirements of the working world".
We don't take children to see 18-certificate slashers, or read aloud to them from the newspaper crime pages, so why subject the little 'uns to this horror?
There are some things – and office stationery wars are one of them – which young minds shouldn't have to contemplate.
Hopefully, Primary Futures will do its best to ensure age-appropriate talks, but even if the secret hope is a new generation of obedient wage slaves, it won't work.
One teacher friend of mine tells a story about asking a class of four-year-olds about their career ambitions. A firefighter? A doctor? A social media strategist, perhaps?
One hand shot up faster than all the others. "Miss, when I grow up, I want to be a monkey."