A few months ago, in London, we went to see Mike Leigh's film Happy Go Lucky. It was pure joy, one of the funniest movies I've seen in ages, though with sombre undercurrents. I fell in love with the main character, whose sole purpose in life seems to be brightening the lives of those around her - except her congenitally miserable driving instructor, who's driven perilously close to insanity by her sunny demeanour.

There was only one aspect of her personality that briefly jarred with me, and that was her response to the theft of her bicycle at the beginning of the film. "Oh, no, I didn't even get a chance to say goodbye", she chirps, and cheerily tootles off to take driving lessons instead.

I reckon I've owned about fifteen bikes since that first Halfords racer I bought to save on the 5p bus fare to school, and thirteen of those have been stolen. My reaction is anything but happy go lucky: a moment of confusion (maybe I just misremembered where I left it?) followed by blind, murderous rage - the kind where, if someone put the cowering culprit in front of me and handed me a loaded Kalashnikov, I'd pull the trigger with scarcely a moment's hesitation.

The last time it happened was in New Orleans at the end of last year. I'd borrowed Pam's bike, and left it locked right outside the main entrance to Wal-Mart on the city’s most oddly named street, Tchoupitoulas (talking of shibboleths, if you can spell and pronounce it correctly, it means you've finally arrived in New Orleans).

When I came out twenty minutes later, it had vanished. Once the rage had subsided a bit, I reported the theft, but even though it took place right underneath the security cameras Wal-Mart allegedly uses to spy on employees thinking of joining a union, the police weren't interested. Though to be fair, they do have rather more important things on their minds at the moment, like doing something about New Orleans' status as the nation's murder capital.

Anyway, it probably serves me right for shopping at Wal-Mart. Last year, I was stung by a wasp as I walked in to one of their stores, which left a huge, disfiguring crescent-shaped blister below my eye for several days. Someone up there is trying to tell me something.

Now that we're back in New Orleans, I've bought Pam a replacement bike, and also one for myself. I’m ashamed to say I bought it from Wal-Mart, and it cost a shockingly cheap $68 – some family in Guangdong is probably going to bed hungry tonight because of me.

It’s a perfectly good bike, with 21 speeds (a bit pointless when you’re living below sea level and the nearest hill is a few hundred miles away) and front suspension (anything but pointless on this city’s third-world potholed roads). I bought the cheapest one I could find, so that when the inevitable happens and it’s stolen in six months’ time, I won’t mourn it too much.

Incidentally, bike theft hit the headlines in the UK last month when David Cameron, the leader of the opposition Conservative party and the person most likely to replace Gordon Brown as prime minister, had his stolen in London’s Notting Hill. I was very amused to see that he’d chained it to a bollard (do you have that word in US English?) about three feet high, so the thieves simply lifted it over the top. Duh! And this is the man that could soon have his finger on the nuclear button…