Dom Joly: It's 50p a swear word... and the pot stands at £75

Idon't know where she got the idea, but Parker, my daughter, suddenly produced a fully decorated swear box and announced that there were new rules for us all to follow. It was going to be 50p per swear word, and she and Jackson would split the proceeds at the end of each month. It was all very entrepreneurial and there was no way we could refuse without setting a pretty bad example.

I decided to lay down some rules of my own: we would accept her terms, but we would deduct 50p every time she or Jackson said "I'm bored", "Shut up" or "I hate you". Ground rules agreed, we were off.

The first morning, which was the usual nightmare of trying to get the kids up, fed and off to school, Stacey snapped: "For fuck's sake, we're late. Dom, get out of fucking bed, you lazy bastard." The kids pounced and charged her £1.50. Jackson was particularly vigilant and marched her off to the box to check she put the money in.

Since then, it's got worse and we're down about £75. Admittedly, it has made me think about my language, and I've started saying "fudge" and "oh gosh", like some posh schoolboy from the 1920s.

We've had a real dispute over a couple of rulings. I've been charged £2 for "damn". Personally, I don't think this counts as a swear word, but the kids insist it does. I went to Stacey for a ruling and predictably she sided with them. It took me back to when I was a lad in Lebanon and my then best friend was a boy called Rory, the son of the Quaker headmaster of my school.

We were playing quite normally in our garden. I can't have been more than six and we were probably building man traps. I used to dig huge holes in the garden paths and cover them with bamboo and pine needles. Then I'd wait for a member of the family to wander down, fall in and break an ankle. Ah, childhood. But I digress.

So Rory and I were playing and, for some reason (maybe the sharpened bamboo spears wouldn't sit properly in the hole), I said "damn". Rory looked totally shocked: "I'm going to go and tell your father that you said 'damn'." I was appalled at this treachery, but pretty sure my father would hate him more for sneaking. I was right, and Rory and I didn't stay friends after that.

Our biggest area of contention at home is blasphemy. Jackson follows me round the house waiting for me to say "oh Jesus" or "for God's sake", two of my favourite expressions. I tried to get a ruling excluding these from punishment, on the grounds that I'm an atheist and don't consider them to be swear words. Parker looked totally shocked. "But Dad, you're taking Our Lord's name in vain." It's difficult to argue with them on this point, even if you are a sinner and an unbeliever. I suppose I don't want them saying "Jesus" all the time, in whatever context.

My new TV show started last week. It's after the watershed, so swearing is allowed – except by my children. They Sky-Plussed it, then went through it with a fine toothcomb, and extracted £4.50 out of the first episode. I've gone back into the edit and removed offending items from the next shows – it's just getting too expensive.

I'm actually quite pleased with the swear box – it has made us think a bit more about how often we swear and cuss without thinking about it. I now go into the garden when I'm feeling frustrated and unleash a volley of invective behind the rhododendron – it doesn't endear me to the neighbours, but it's a lot cheaper.

Dom Joly's 'Complainers' is on Channel 5 at 10pm tomorrow