By Victoria Coren, The Guardian

If Zinedine Zidane played online poker, he would never have headbutted Materazzi for a comment as harmless as "Your mother is a terrorist whore". Relative to the chat-boxes on some gaming sites, that remark would be considered friendly banter.

In the old American road-gambling days, you wouldn't swear at poker opponents for fear of being shot over the table. Even in British games, politeness was the advisable default mode, lest you received an invitation to join the victim of your sarcasm in the car park.

To this day, a certain etiquette is expected in live poker games. "Slow-rolling" (taking too long to reveal the winning hand at the end of the betting) is considered inflammatory. Acting out of turn, crowing when you win a pot, or insulting a loser, is also extremely bad form.

You can't slow-roll online, as the computer reveals your hand for you. It mechanically prevents you from acting out of turn. But you can choose to shout vile curses at your opponents, because they can't hear. That's the internet for you: when a guy is looking at online porn in the privacy of his own home, he also does things that he shouldn't do in a crowded room with a lot of people watching.

But some people, protected by the anonymity of the computer screen, enjoy typing their insults into the chat-box. The other day, I watched two players trade invective on Paradise Poker. As the lines at the end of this column declare every week, Paradise is my website of choice - I write poker tips for them, and they sponsor me to play some live tournaments - but I was playing under my unisex screen name. I decided to tell them I was female to see if it made any difference. Charmingly, the insults were toned down and the chat-box restored to its proper function (to debate hands calmly, throwing in the odd bit of small talk or funny comment to re-create the banter of a social game).

Clearly, the players were aware that it isn't very nice to abuse strangers (or anyone) in this way, and were actually quite capable of controlling themselves. What they may not know is that it's also a more lucrative strategy to stay friendly.

You've got a week to work out why that might be, before I spell it out next Friday. In the meantime, remember: however significant the money, poker is a recreational activity that shouldn't be used to make people feel miserable.