Now that that day is past, I can reveal the source. My friend has read a number of books by Alexander McCall Smith, the author of The No. 1 Ladies' Detective Agency. One book, http://en.wikipedia.org/wiki/44_Scotland_Street]44 Scotland Street[/url], included (as I recall from her telling of it) the adventures of a female anthropologist who was researching South China Sea pirates. She found a South China Sea pirate community and entered into it and became a part of the community, as anthropologists will do in order to research those communities. They would make mention of their pirate activities, but never offered any details, apparently because she was not yet completely trusted. Then she caught wind of that the men were preparing to depart on a pirating expedition. She followed the men's boats to a remote island and observed them entering into a building. She crept up to that building, up to one of its windows, and raised herself up to peer inside and ... that installment of the story ended. And it was several installments later that the readers finally learned of her fate. The piracy that that community engaged in was the illegal copying of CDs and DVDs.
A towel, [The Hitchhiker's Guide to the Galaxy] says, is about the most massively useful thing an interstellar hitchhiker can have. Partly it has great practical value. You can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapours; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a miniraft down the slow heavy River Moth; wet it for use in hand-to-hand-combat; wrap it round your head to ward off noxious fumes or avoid the gaze of the Ravenous Bugblatter Beast of Traal (such a mind-bogglingly stupid animal, it assumes that if you can't see it, it can't see you); you can wave your towel in emergencies as a distress signal, and of course dry yourself off with it if it still seems to be clean enough. More importantly, a towel has immense psychological value. For some reason, if a strag (strag: non-hitch hiker) discovers that a hitchhiker has his towel with him, he will automatically assume that he is also in possession of a toothbrush, face flannel, soap, tin of biscuits, flask, compass, map, ball of string, gnat spray, wet weather gear, space suit etc., etc. Furthermore, the strag will then happily lend the hitch hiker any of these or a dozen other items that the hitch hiker might accidentally have "lost." What the strag will think is that any man who can hitch the length and breadth of the galaxy, rough it, slum it, struggle against terrible odds, win through, and still knows where his towel is, is clearly a man to be reckoned with. Hence a phrase that has passed into hitchhiking slang, as in "Hey, you sass that hoopy Ford Prefect? There's a frood who really knows where his towel is." (Sass: know, be aware of, meet, have sex with; hoopy: really together guy; frood: really amazingly together guy.) —Douglas Adams, The Hitchhiker's Guide to the Galaxy