We have all been there: an enclosed space, be it a bus, train or lift, and a mobile phone rings. The owner answers and, without fail, the conversation begins with a declaration of the person's precise location. The call then continues at full volume and the audience is given no choice but to hear some detail about the owner's personal life. For some, the experience is mildly irritating; for others it is deeply infuriating.
Now, in an attempt to crack down on such anti-social behaviour, one of South Korea's largest wireless operators, KTF, has launched a campaign, dubbed 'Motiquette', which asks the millions of mobile users to consider others when using their phones.
It has issued a list of do's and don'ts, ranging from switching mobiles to vibrate (or 'manner mode' as it is known here) and not starting a conversation with someone who is driving, to speaking in a low voice when taking a call outside.
The recommendations are simple and obvious, and campaigns like this should not be necessary, except that South Koreans' passion for modern telecommunications, coupled with their liberal interpretation of personal space, mean that the potential for wider irritation is often sacrificed for instant personal gratification. Like many other Asian countries, South Korea has embraced the mobile phone. More than three-quarters of the population of 48 million are now estimated to own one.
Young South Koreans in particular appear to be linked umbilically to their phones. In a recent survey, students reported feelings of unease or even panic if they were without their mobiles.
Walk down any main street in Seoul and it can often feel as though the art of face-to-face contact has been lost among the hordes of people with phones stuck to their ears. I have heard mobiles ringing at weddings, in classrooms, and people taking calls in the middle of films.
Yet there appears to be a remarkably high level of tolerance for such obvious rudeness. The explanation? Perhaps population density is one reason. South Koreans do not have the luxury of a wide and clearly demarcated personal space.
Then again, maybe it is because there is little concept of noise pollution in a country where customers have become immune to shops which belt out pop music through concert-sized speakers. Or perhaps it is the lack of 'civic consciousness', which long-term foreign residents are apt to remark on.
The motiquette campaign has at least got South Koreans talking about how to behave properly. If they decide to discuss it on the phone, let's hope that they can do it quietly, at least.