Every parent of teenagers knows that curious paradox by which we live today: that, instead of our children having to mind their manners in front of grown-ups, it's the grown-ups who have to mind their Ps & Qs in front of the children.
There are few more dismaying sights than the curled lip and the moue of disgust on the face of your delightful offspring when you try to use hip slang, or make a clever pun, or mention "my gay friend Jeremy" instead of "my friend Jeremy", or say "pot" instead of "weed", or go to a fancy-dress bash in a Tin Man costume that you bought in a party shop in Wandsworth, or wear your "Live Fast, Die Young" T-shirt, or admit that you're having trouble finding GoogleEarth on your iPhone.
Of course, intergenerational embarrassment affects every generation, doesn't it? I remember writhing with mortification when my coolest friend from school and I were watching Bob Dylan on TV in my family living-room, some time in 1967.
"My God," said my father with feeling, "that Dylan feller really makes that harmonica talk."
"Please Dad..." I said, blushing violently.
"It really, you know, blows your mind, doesn't it?" he continued.
"Dad, I'm begging you..."
"He really – what's the phrase – puts it in the groove, don't you think?"
"Aaarrgghh!" I remember covering my face with both hands and rocking wordlessly back and forth, wishing to God my friend wasn't around to witness such middle-aged folly. But scroll forward 40 years, and my own children make similar gestures of kill-me-now horror these days because I have turned into a Tragic Senior.
Help for the perplexed is, however, at hand. A new book, by the American novelist and journalist Pamela Redmond Satran, tries to confront, head-on, the battleground of style, clothing, vocabulary and attitude that registers today's over-forties as being tragically over-the-hill, washed-up, redundant and moribund in the eyes of their children and their children's friends. It's titled How Not To Act Old: 185 Ways to Pass for Cool, Sound, Wicked, or At Least Not Totally Lame, and contains a good deal of droll wisdom and pin-sharp jokes.
Ms Satran's book is a spin-off from her website, Hownottoactold.com, whose raison d'être she explains with admirable economy: "The point here isn't to act like a 26-year-old. God forbid. It's just to learn how not to act like somebody a 26-year-old might snicker at." So – stop going on about how wonderful the Sixties were (that was 40 bleeding years ago). Never say to another human being, of any age, "Are you sure you're going to be warm enough in that?" Never volunteer the information that a policeman, doctor, politician or rock star "looks about 12", because it'll make you sound at least a hundred and twelve. Don't send any more greetings cards. Never leave dried flowers around your living quarters. ("They are the antimacassars, the china figurines of today... the decorating accent of the middle-aged.") If you must use email (young persons would far sooner use texts or Facebook or LinkedIn or Plaxo or Twitter), don't use punctuation, formal greetings or full sentences, unless you want to sound like Rip Van Winkle wheezily addressing his great-grandchildren.
Conversely, don't try too hard to sound street-smart by saying "sick" to mean good, or "safe" to mean physically well, or "I'm all about linen jackets right now" because you heard your 14-year-old daughter say something like it the other day. Horrible young persons will know you're eavesdropping, to hear useable fashionable slang, and they will take the piss. I once let my son convince me that the phrase "It was well weapon" (meaning truly excellent) was all the rage in Teen-land, until I used it aloud one day in teenage company. The memory of their hysterical laughter haunts me still.
Amid the more predictable counsels for the incipiently middle-aged (stop wearing Speedos when you've a Fat Upper Public Area, stop turning up the volume on your TV, stop watching Midsomer Murders), there are some real gems of insight about modern yoof. Such as: many kids never wear watches now because they check the time (with one hand) on their mobile phones. Many kids, possibly the same lot, never ask for directions because they can check their journey details on GPS or Mapquest or Google. And they never leave voicemails; they just assume that the person they phoned will see their number in the Missed Calls slot and ring them back if they feel like it.
What else? If somebody says "Thank-you" to them, they'll respond not with "You're welcome" or "My pleasure", but with the Australian "No problem". (I've just tested this theory by thanking a 25-year-old in my office – and it's 100 per cent accurate.) Ms Satran is also spot-on when she suggests that today's 16-to-24-year-olds live in a state of weird positivism, articulated by their mantra, "It's all good." If you carp or complain, rant or rave, or have big, tearful confrontations with them, as your parents once did with you, they'll think you've gone over to the dark side. You'll seem tyrannical and shouty, rather than impressive and mighty.
Ms Satran comes across as an immensely likeable dame in her fifties, who has done a lot of close-up research of teen and early-20-something behaviour; but she has also inspected her own behaviour to see what works. As a result, she's able to recommend that the only expression of middle-aged enthusiasm that goes down well with the young is the word "Yay!" accompanied by a little dance. She knows that if you're subjected to a chilly silence by a teen, you must not panic or send a flood of worried texts or emails. You just chill out, wait for a text to arrive, then wait a few hours before replying, using fewer words than their message. It's all about brinkmanship. She's also grasped the crucial fact that wearing clothes that match, or living in décor that blends together, is a sign of insecurity and fatal elderly-ness.
I didn't buy her pronouncement that it's disastrous to display to young persons a fondness for Bruce Springsteen (who held a god-like status among young concert-goers in Hyde Park last summer), but otherwise it's hard to fault her conclusions. I admired her droll, Dorothy Parker-ish view of inter-generational relationships, and her caustic advice. She missed only one thing really – that there's nothing more truly ageing than sitting around worrying about just how ancient you seem these days...
'How Not to Act Old' by Pamela Redmond Satran is published by HarperCollins (£9.99). To order a copy for the special price of £8.99 (free P&P) call Independent Books Direct on 08430 600 030, or visit www.independentbooksdirect.co.uk