Black Friday came and went and everyone was much happier for its having been. Then, after a weekend of unpacking purchases and nursing wounds occasioned by flying shrapnel from errant shopping trolleys, came Blue Monday, when some might have surveyed bank balances vastly diminished by the acquisition of price-reduced Persian carpets and wondered what got into them. (Not me. I love my new Kashmiri rug. It is exactly the right colour to disguise pools of cat vomit, so tuna warmly regurgitated on a Monday morning makes its presence felt only when you step in it.)There has been a lot published about the term "Black Friday". Peddlers of ignorance claim it stems from the days when slave merchants would put their human wares on sale. This is utter nonsense.story_article_left1The excellent myth-busting site Snopes.com points out that the expression was coined more than a century after the abolition of slavery.In the early 1960s, reporters in Philadelphia began using "Black Friday" to describe the bad mood of harassed policemen trying to control traffic and tomfoolery on the day after Thanksgiving, when workers took the day off to go shopping or to baseball games or simply to cause hungover mayhem in the streets.If we return this phrase to its roots of heavy traffic and bad driving, some might say every day is Black Friday. But let's move on to Blue Monday, which is similarly tainted by unfounded speculation.Since 2005, a spreading internet rumour has claimed that "scientists have identified" a particular Monday in January as the statistically most depressing day of the year.Again, trusty Snopes explodes this spurious garbage, tracking it to an article paid for by a public relations firm working on behalf of a travel company (the message, naturally, was that we can beat the blues by going on holiday).The scientist in question was a part-time tutor who became the first in a series of scientific "professionals" who received financial recompense for telling the public how depressed they were and what products and services would help them feel better.There may not be an objectively proven Blue Monday, but it is still a useful term for days of blistering chaos that unsurprisingly have a habit of occurring right after a restful weekend, during which we are all more prone to putting the car keys in strange places and forgetting the simple fact of how hangovers are caused.story_article_right2"The Day When Everything Went Wrong" is a popular school essay topic assigned by teachers whose brains are too Monday-muddied to think of more imaginative subjects. Perhaps the resulting litany of smoking pans, exploding parents and insane pets that rampage through the chaotic lives of others helps them appreciate the calm haven of the classroom."Chaos" is an interesting word. It comes from the Greek khaos, meaning an abyss or a gaping void, which in etymological terms is a close cousin of the word "yawn". If you yawn while driving with your car window open and a large butterfly flies into your mouth, chaos could ensue.We use "chaos" to describe a situation in which the normal rules of functioning have been turned upside down, but in scientific circles chaos is not nearly as chaotic. Mathematician and meteorologist Edward Lorenz, who was one of the first to study chaos theory and who coined the term "butterfly effect", defined chaos as: "When the present determines the future, but the approximate present does not approximately determine the future."In layman's terms, this means that a tiny change at the beginning of a process could result in one of several million unpredictable outcomes. Traffic is chaotic. So is the weather. So is a column that began with the intention of giving advice on how to clean a Kashmiri carpet but got knocked slightly off course and flew away in an entirely different direction.E-mail your observations on words and language to Sue de Groot on degroots@sundaytimes.co.za or follow her on Twitter: @deGrootS1..