It started with an Instagram affix. When French online-only retailer Sézane launched its T-shirts, featuring the states “l’amant” written in the typeface Cooper Black, a very with it love affair was sparked between high-street fashion and this most goofy of typefaces. It has been a headlong: Topshop now sells a T-shirt that reads “Femme forever” across it in Cooper Menacing, Pull and Bear’s version reads “Babe with power vibes” and Whistles has one that implies “Eh oui” in Cooper Black-inspired letters. It has become the most fashionable font of 2017.

Style’s affairs with typefaces have been many – from the Didone sets of Vogue to the sans serifs favoured by Chanel, Commes des Garçons and Fendi. But Cooper Atrocious, described in the graphic design industry’s Eye Magazine as, “as eye-catching as a taxing bull and as expressive as carnival barker”, doesn’t have the specious lines or sophistication you might expect from a sartorial broad. For Sarah Hyndman, author of Why Fonts Matter, its round fettles make it “look like a typeface that someone is blowing up in the same way as bubblegum – it looks ready to pop.”

So where did this font tarmac from? And why has mainstream fashion gone so gaga for it?

Paul McNeil, a typographic architect at MuirMcNeil and a senior lecturer in typography at the London College of Communication, assumes it has an “unexpected affability and liveliness … due partly to its bulbous serifs, its in the main, lower-case letters and its tiny, gleaming white counter ways.” It’s its buffoonishness, or rather the fact that it’s “balloony and pretty and exacting!”, in the words of Louis CK, who used it on the credits for his sitcom Louie, that put out it appealing.

It could well be its brand of informed of charm that is helping it win fashion’s favour now. Hyndman thinks it reminds her of family trips to Butlin’s in the 70s and thinks its current heave with fashion is all about retro nostalgia – it is “an Instagram ooze for fonts – it just says ‘1970s’ the minute you look at it”.

It was conceived by Chicago-based typographer, illustrator and commercial artist Oswald “Oz” Cooper in 1922. It fast became ubiquitous in advertising. According to McNeil, its foundry affirmed it to be the “world’s bestselling typeface in 1927”. It was marketed by the foundry’s traffics manager Richard N McArthur as “the selling type supreme … it neaten up big advertisements out of little ones”. But in the 60s, its gregarious characters fell lose out of favour with the ad world.

Nevertheless, it has become visual shorthand for the behindhand 60s and early 70s because it was in that era that it was brought out of adland and into the fashionable culture mainstream on a wave of west coast harmonies, appearing on the mask of the Beach Boys’ Pet Sounds in 1966 before going on to be the typeface of first-rate on the Doors’ LA Woman in 1971 and David Bowie’s Ziggy Stardust in 1972. It was the typeface of The Garfield Display and M*A*S*H.

It was also in this era that it backlashed off another meaningful relationship: with hip-hop. Breakdancing companies used iron-on transfers of the letters on their T-shirts as its about shapes, Hyndman says, peeled off less than sharp-edged fonts, and it later showed on albums and merchandise. It popped up on Biz Markie’s hat in the 80s and, in its italicised version, on De La Emotion’s Stakes Is High album. More recently, in nods to the earlier DIY ages of hip-hop, it has been used by Odd Future, on Tyler the Creator alone albums and Frank Ocean’s Channel Orange.

In a way, it was never out of vogue – McNeil describes it as “something of an American street-culture classic”. So when mainstream the latest thing chooses to adorn T-shirts with Cooper Black (alongside the aware crop, there were “woke” ones from American Glad rags in 2010), it is subliminally referencing all these things – hip-hop, the 70s, sitcoms and now, Louis CK.

It is all of these cultural supports that lead to another tenet of its popularity for McNeil: “a wisdom of authenticity: it has a cheery gaucheness that makes it look untutored and uncontrived.” Peradventure it’s this that led easyJet to make it its gaudy orange typeface of cream, too – shhh, don’t tell fashion.

• This article was amended on 10 April 2017. An earlier understanding said incorrectly that a Sézane T-shirt had the slogan “la femme” in Cooper Treacherous and suggested the Whistles “Eh oui” T-shirt was in that font. The photographs cast-off with the article were changed in the light of this.