I have a friend, Eleanor, with whom I share so many private jokes that if one of us were involved in a crime and the police impounded our phones, it would take Alan Turing-levels of expertise to decode our text conversations. Think Anne Lister’s diaries, but with the cry-laugh emoji after every single sentence.

One of the strongest bonds people can have is a shared sense of humour. As someone who basically finds everything funny, I have multiple versions of this. Eleanor and I often share very dark jokes, but also run amok with absurdism. I can fire witticisms back and forth with my friend David like it’s a Wimbledon final. With Tshepo, we reference our past shenanigans and shriek with delight. Every single time we hang out we add another one to the canon.

Chris and I love each other so much that we rip each other to shreds most days and, along these lines, there is a long-running trope that he is a cuckold, because I am having an affair with his wife. The WhatsApp group my school friends and I belong to is filled with quotes that only we can comprehend. I have a colleague whose office I slip into when she’s not in it and put up posters. One time, it was just a huge blown-up photograph of myself.

These little-and-often gifts of mirth are as revitalising as a vast intake of breath. All I need to be cheered on a bad day is an unexpected screenshot landing in my inbox of something that only a friend, or a small group of friends, understand. This is usually followed by increasingly zoomed-in screenshots of the same thing, or quickly searched and sent variations on the theme. Spontaneity and repetition are key to keeping private jokes alive. Riffs are built upon like Led Zeppelin songs.

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But it isn’t imperative to have a long history with someone to share a private joke. Sometimes they are fleetingly possible with strangers. Many a time I have caught the eye of a fellow passenger or queue member when something hilarious has happened, two perfectly unknown-to-each-other individuals mutually stifling smirks. This is best when nobody else has cottoned on, or is too mature to find the situation amusing. (It perhaps shouldn’t be funny when someone trips up… but it just is – sorry. Ditto spoonerisms at live events.)

I am not entirely sure why esoteric jokes and references make me so happy, given that I can also derive much joy from humour that goes viral worldwide. But I imagine it comes down to a close sense of community and belonging. “You had to be there” goes the phrase, and God, it’s just beautiful if you were.