What’s in a wink? That’s a question scientists have pondered for centuries but have never quite put a lid on.
Medics tell us a wink is the momentary closure of one eye – controlled by the orbicularis oculi muscle in response to brainstem activity.
And psychologists define it as an informal mode of non-verbal communication usually signalling shared hidden knowledge.
But winking is the most ambiguous gesture that the human face can make.
Depending on the context it can convey affection or disdain, friendship or deceit, solidarity or disparagement.
So in order to decode the secret message the winkee and any watching wink-catchers need to understand the bigger picture.
Which is why we knew in a blink of an eye what Tory winker Dominic Raab was saying to Angela Rayner at PMQs on Wednesday.
He started by taking a pop at Labour’s deputy leader for daring to go to the opera – branding her a champagne socialist.
But then he threw her a cheesy wink that Sid James would have been proud of. And that split-second facial “tell” told everyone watching that the Tories have done nothing to change their culture of misogyny and macho entitlement.
It’s not long since the PM was threatening “the terrors of the earth”on any sexists in the party after one of them accused Rayner of weaponising her legs to try and distract him.
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And this week Boris was displaying his feminist credentials by accusing Vladamir Putin of “toxic masculinity” and saying a woman would never embark on “a crazy, macho war”.
So he must be pretty peeved with his Deputy for the cringe-worthy nudge-nudge, wink-wink moment.
Of course, Raab’s team say we all got it wrong – and he was actually gesturing to the shadow Scottish secretary Ian Murray who had muttered something off camera.
So is the whole affair just a load of blinking nonsense or does Raab’s wink show us a bigger picture?
A sign that sexism, entitlement and disrespect are still rife in this Tory government.
And that none of us can afford to turn a blind eye to the dangers.