This just in - "poo" funniest word in the world according to snap poll of four-year-olds.

When our eldest Charlie started school in September, I expected that he was about to embark upon a rich and varied journey of knowledge-seeking. Little did I know that the main thing he would be learning was the value of a good rude word in the right place.

He has yet, however, to realise the subtleties of swearing; ie, that less is more and that rude words have more power when used sparingly.

To this end, "poo" is being bandied about at any given opportunity. And not just "poo" - "poo-poo" seems to be the cussword du jour among Charlie and his friends at school.

I'd like to put it on record now, for any other parents at the same school who might be reading, that this certainly hasn't come from our house, and neither has its associated phrases "pee-pee" and "wee-wee".

They've become so commonplace that the children greet each other with them when they meet in the playground prior to the bell going off in a morning: "Hello, poo-poo." "Hi, pee-pee."

Charlie has also taken to, when queuing up to get into class, waving me off with a "Bye-bye, poo-poo."

Well, it's nice to know I instil a bit of respect.

I suppose we shouldn't be too alarmed by this, though. Although it is very annoying and slightly embarrassing, there's far worse that he could be saying. I suppose all that's to come, although perhaps by then he'll have the good sense to keep his swear-words to himself, or at least use them among friends only.

I remember when I first learned the delights of the extended vocabulary that is cussing, I took great pains to hide it from my parents.

This was for several reasons. The first was that when I was a young shaver I told my assembled family a joke that began with a graphic description of a boy and girl in a bedroom who were doing something I had words for but no real understanding of. I didn't get to the punchline, surprisingly enough.

Secondly, when you're an all-knowing young person, you think you're so clever and cosmopolitan that the words you use on the street aren't actually known to your parents, and you want to protect their poor, old selves from rudeness that would just flummox them.

Back to the relative innocence of poo-poo, though, Charlie has started to take it to extremes a bit. Tomorrow he is starring in his first school Christmas concert. He has been given the role of "villager", about which we are immensely proud. Hey, not everybody could be a shepherd back in Old Testament times, you know, and to be honest it wasn't that great a job anyway - long hours, late nights and not much to do apart from watch the sky on the off-chance a star happened to move around a bit.

Anyway, as part of the concert Charlie and his fellow villagers have to sing "Away in a Manger". He's been treating us to some lovely renditions of the old Christmas favourite over the past few days, except when he's in a particularly boisterous mood and he bellows out: "Away in a POO-POO!"

We await tomorrow afternoon's performance with bated breath...