I looked like one of those chimps in the PG Tips Tour de France advert and could not go out on this bike without attracting the attention of every would-be comedian in central London

I sincerely believe in the adage that "there's no such thing as a free lunch" - you usually find they have some exchange in mind, like I buy you a mess of potage, you give me your birthright. I also hate the fact that the only people offered the free stuff are the people who have more than enough money to buy it in the first place. So, unlike many celebrities, I have never been very keen on accepting "freebies" - ie, gifts, holidays, trinkets given by manufacturers and retailers in the hope of endorsement or recommendation. For years I used to refuse the magazines such as Ms London and 9-5 that are handed out at London tube stations with angry cries of "What kind of star do you think I am that my soul can be bought with a crappy magazine?" until I realised that they were offering them to everyone and not just to me.

Actually, I have a theory that there is some inherent balance built into the universe whereby every free gift and junket has a curse attached to it, so that any pleasure or advantage gained by the gift is cancelled out by the trouble it causes - it's just Newtonian physics, really. For example, I have a friend who did some work for British Airways and was rewarded with a plastic card that was supposed to entitle him to an automatic upgrade when he flashed it at the staff on the check-in desk, but instead the card seemed to induce the only examples of bolshevism outside North Korea in the people behind the BA counter: their eyes would often glow red and instead of being bumped up, he was often bumped off flights and was often forced to travel back from places like Singapore by bus.

The one time I succumbed to the greed of getting something free it also turned out badly. A major bicycle manufacturer offered to build me a bike a few years ago and my greed for more bicycles (I have nine) got the better of me. But somehow I just never took to this machine: a racing bike that was specially designed for me, which had a frame so tiny that I looked like one of those chimps in the famous PG Tips Tour de France advert and could not go out on it without attracting the attention of every would- be comedian in central London. As a final proof of what unearned gifts do to you, you only have to look at those who are habitual freebie-grabbers - Joan Collins, poor woman, for example - she's only 29, you know.

I definitely think there is a curse on these things, similar to that which attends those who loot the culture of others. You'd think we'd all have seen enough movies of mummies coming to get back what was theirs to have learnt our lesson. And if that doesn't convince you, look at the trouble Paul Simon is having with his hair! But oh no, there are always some people who are prepared to risk conjuring up some awful fate for themselves. I'm thinking in particular of those people who are in the business of faking Australian Aboriginal art.

Traditional Aboriginal art was done in sand using ground ochre, feathers, hair, clay, plant fibre and blood, and these paintings were prepared for strictly secret men's or women's ceremonies and were destroyed at the end of the rite. It was not until 1971 when an art teacher called Geoffrey Bardon at Papunya School in central Australia introduced some senior Aboriginal men to acrylic paints that they were inspired to transfer the desert "Dreaming" stories to board, thus recording these ceremonial designs in a permanent form for the first time. The fact that these paintings can now sell for large amounts has been followed by that sure sign of artistic success - the art faker.

Unscrupulous white people have started faking Aboriginal art and selling it as genuine. They simply take the sacred symbols, such as those for a "Rainmaking Dreaming", and reproduce them in random order, but it is here that the risk arises. It is possible that by meeting with the symbols of powerful magic they do not understand that they could accidentally create a dangerous spell which could affect all who come into contact with the painting. It might be that they may have produced a "Trousers Explode While Having a Late Supper With Ned Sherrin Dreaming" or "Develops an Erotic Obsession with a Pumpkin in Safeway Dreaming".

In fact, come to think of it, I own an Aboriginal painting myself. I bought it from a shop called something like Creative Native or Fabbo Abo in Perth, Western Australia, owned by people in sandals and beards, at least one of whom was a woman. And of late I do seem to be spending an inordinate amount of time in the vegetable department at the supermarket, dreaming of Halloween.