LIVING here for 12 years and deaf to the melodies of Cantonese, the surprises never stop coming. I have only just discovered why Hongkong people do not use shopping baskets. They are rude. They are downright lewd, licentious and ''blue'' or - if you had congee on your cornflakes this morning - ''yellow''. Two gweilos, one from Pearl and Dean and the other from the MTR, have been sent on an eight-year compulsory language course and bean curd diet without remission for having put up environmental campaign ads on stations actually exhorting people to use baskets in preference to plastic bags. Apparently laam meaning basket, if mispronounced by even a whisper of a demi-semi-octave, becomes a colloquial expression for the male genitals. Women in these parts are not even allowed to think on the subject of ''baskets'', let alone breeze into shops bellowing for them. Had he made it out here, Bateman the cartoonist might have drawn a hapless woman in the middle of a store, surrounded by taitais and amahs, some in a swoon, some with their hair standing on end. It would have been titled ''The Woman Who Asked The Shopkeeper For a Good Strong Laam.'' To actually wander through the malls and markets, swinging a laam on your arm is enough to invite stoning, which, I now realise, is why you never see it. This might also explain the dearth of ethnic basketwork in the Guangdong region and why Hongkong never ratified the Basket Three Accord of the Helsinki Agreement. On the other hand, it confounds all explanations of the flash fire popularity of basketball- or laam kau - a word which can explode from both ends. Mr Cheung of The Professional Teachers Union hopes the incident will make the MTR more aware of its social responsibility. I thought its social responsibility was to shift a billion or so folk a day and not worry about haam sap double entendres. What I want to know is how such right thinking people as Mr Cheung and the moralists standing in the slips on the platforms are so aware that when reference is made to a nice wicker basket with a flower design on the side, people's minds are flitting to men's flies. It may come as a surprise to Chinese speakers that, given the universality of imagery, ''basket'' has exactly the same alternative meaning in English. You don't have to even mispronounce it slightly. That would make it ''biscuit'' which, sadly, has nothing smutty about it at all, quite unlike ''crumpet'' which can barely be used in its original form any more. We could go on and, one day, we will. Suffice it to say this does not deter English matrons from using the word. It does not banish ''the vessel for containing shopping, laundry, wastepaper'' (Webster's) from the realm of human experience. My old mum can go into the local hardware shop and say in an ordinary voice: ''I'll have a nice big basket, Mr Ball, if you please,'' without other customers rushing outside to call the language police. This was doubtless the downfall of the two gweilos. Their mothers probably did the same. The trouble for them was that their poster got in even deeper than laams . It repeatedly mentioned gaaus. I have come to realise that there is hardly anything left, animal, vegetable or mineral that is not a gaau of some sort or another, but I'm damned if I knew it meant ''plastic'' too. With the ad inveighing heavily against plastic bags, gaaus were all over the copy like mines. As the two shaven headed gweilos spoon through their root soup, they may care to reflect that the gaau sound can be made to mean more things than there are days in the week. So, you can sit up in bed one morning and shout ''nine'' or on another ''dog'' or, if it's Saturday and you are feeling abandoned, most prominent item in the aforesaid ''basket'', which it also means, and empty the apartment block. There is no getting away from the gaaus. You must have almost been able to hear the grinding of teeth and loins on the edges of those platforms all the way down the system. Teacher Cheng will nod his head approvingly when I confess that I have learned something else from this incident. Given that supermarket bags represent a collision of meaning between proper plastic and colloquial basket, it is no wonder that people crumple them up and throw them away after use.