Last week, Another Newspaper managed to print a guide to World Cup French without citing the most crucial phrase of all. This is the formula that voices mild dissent at the verdict of the match official and runs: aux chiottes, l'arbitre! A further burst of connard or trouduc will confirm your reputation as a true fana. At the end of the game, you may feel gutted (hyper decu) or, indeed, sorted (bien dans tes baskets). But only the most incorrigible arsouille (yobbo) will then stagger down to the troquet (boozer), check out the top totty (vise les supernanas) and get bourre comme un coing.

A meagre pounds 5.99 investment in Harrap's new two-way English-French slang dictionary - entitled Pardon My French! and decorated by a frog in shades - could liven up the next few weeks no end. Apart from its parade of old favourites (French letter = capote anglaise) and priceless chance discoveries (an overnight bag converts into a baise-en-ville or "shag-in-town"), the volume breeds some knotty thoughts about the deep gulfs that still separate one nation's street speech from its neighbour's.

Sometimes, Harrap's can render slang into slang with a startling bull's- eye precision. At the moment, you may not wish to complain that "some slag's stolen my fags". If you ever did, then il y a un enfoire qui m'a picque mes clopes is just the way you'd do it south of Cap Gris Nez. Yet many of the fresher idioms surface in the form of bland synonyms that miss all the pizzazz of their originals. If I were a boy racer, I'd be well narked (en rogne) to find myself bureaucratically set down as a jeune conducteur imprudent. From the other side, the arcane mysteries of French backslang (verlan or java) can be paraphrased but not really translated.

In the high-rise banlieue, Arabe became beur. That's clear enough. Outsiders - including the BCBG (Sloane Ranger) Parisians - may well lose the plot when a sort of double-backslang kicks in and transforms beur into rebeu. All the same, one snatch of verlan may prove extremely apt when some ringard (nerd, geek, anorak) spends too much time parked in front of the teloche over the coming month: il s'est fait tej par sa meuf (his bird's gone and dumped him).

This head-to-head compendium of insult and obscenity does expose some underlying rifts. Mainstream English slang (surprise, surprise) excels with in-your-face aggression couched in a scabrous, pseudo-sexual idiom. Although it boasts its fair share of bodily-function bravado, French argot can be slyer, even camper, dense with a secret disdain. It will often conceal rather than confront. Then there's the ever-present agricultural tang that makes an innocent tourist's request for onions or leeks into a trigger for teenage giggles. Only franglais offers much in the way of common ground. So have yourself a cool weekend (un cool weekend).

Yet the sheer perversity of slang will often thwart all efforts at conversion. Not long ago, some bloke at the bar (un mec au zinc) admiringly called my jacket "the bollocks". How to explain to even the brightest French learner that the definite article transmutes a mortal slur into warm praise? It's enough to make a baffled English-language teacher forsake the classroom and take up football-writing instead. Which is exactly what Nick Hornby did.