My friend Sam doesn’t waste a single bite of an apple. He crunches through the core, swallows the seeds and doesn’t leave anything behind, but the stalk. In this way, he couldn’t be more different from our mutual friend Megan, who refuses to eat apples unless they’ve been sliced. Sam doesn’t own an umbrella. Megan changes her bedsheets every week. Neither Sam nor Megan particularly love striking up conversations with strangers. When Sam was a child, he had to be taken home from his very first sleepover because he vomited Turkey Twizzlers on the carpet.

These are the kinds of incongruous facts that people know about their loved ones in movies – as Harry famously said to Sally, “I love that you get cold when it’s 71 degrees out. I love that it takes you an hour and a half to order a sandwich.” In real life, we pass the time talking with our friends about their children, co-workers, exes and eccentric family members, but we don’t always hear about the meaningless minutiae that makes up their daily lives. This is why I sincerely recommend that everyone starts doing one thing: ranking your friends.

What an evil and totally objectionable suggestion! Let’s not get things distorted: I do not think that you should rank your friends based on how much you like them, or how cool or pretty they are, or how close you consider yourselves. Instead, you should rank your friends in arbitrary, nonsensical and conversation-provoking ways.

I know about Sam and Megan’s apple-eating habits because one day I posted a simple sentence in our group chat: “Friends ranked by how close they get to the core when finishing an apple.” The resulting conversation was lively – Anya gets right down to a spindly nub (I knew it) and Zoe takes cautious bites and avoids the centre. I now have a 27-second video of Sam eating an apple, core and all.

Last April, someone wrote to the Guardian’s agony aunt about their friend ranking loved ones in a league table. My ranking game is, I hope, the exact opposite of this – not private, secretive, score-keeping, but collaborative fun. It is something your friends can do together, as a group. It is about observing and understanding each other. Categories have included the simple and straightforward: friends ranked by how often they have McDonald’s; friends ranked by how early their bedtime is; friends ranked on their likelihood to miss a plane. Things have also veered towards disturbing specificities: friends ranked on who eats the most artificially blue food; friends most likely to have called home to be taken away from a sleepover as a child; friends ranked on how much they fear death.

I started my rankings spontaneously when I was eating McDonald’s while a group chat was popping off. When confronted with these two stimuli at once, I thought: I wonder who in this chat has McDonald’s most regularly. I ranked my friends and wasn’t especially surprised by the results. The game was a resounding success and, as the days passed, everyone began throwing out different categories and discussing things that we’d never discussed before.

Eleanor Roosevelt is reported to have once said, “Great minds discuss ideas; average minds discuss events; small minds discuss people,” but to me that sentiment has never made sense. How could you possibly discuss ideas or events without discussing people? Still, there’s truth at the heart of it – how many dinners have been spent bitching about a conniving boss or the woman in your industry who is doing better than you but in an annoying way? How often does someone chime in to discuss the way they eat an apple?

And OK, there’s a reason people don’t do this. Observations about the minutiae of life are the stuff of debut novels or really long Instagram captions. Bring this stuff up spontaneously and you risk looking like a quirky manic pixie dream girl who loves blue raspberry.

And yet, entirely accidentally, “the rankings” allowed my friends and I to talk about this pointless, silly stuff often with unexpected results. One dull afternoon, a simple ranking – who goes to bed earliest – provoked a surprising chat. I thought Clara, like me, would go to bed late yet she often has an early night. Why? Clara wakes up early because she has therapy at 7am every day. This was an intimate aspect of her life that she had never disclosed to me before, and it opened up a discussion about our mental health.

The rankings can therefore be a window to self-awareness. As another pal put it: “To be ranked and to rank is to know and fully be known.”

Again, I have to stress that ranking your friends isn’t about scales of good to bad – it’s certainly not about yearbook accolades such as, “Most likely to be a billionaire” or “Most likely to win a beauty contest.” One friend who greatly enjoys the rankings recalls a terrible occasion, years ago, where a group of her pals decided to play “the paper game”. They tore up strips and wrote things on them such as, “prettiest” and “worst bum” – everyone was then given a pile and had to hand them out to whoever they felt fitted the title best. Somehow, my friend says, it was worse when the group decided only to write “nice ones”. She sat there watching one friend accumulate a snow pile of paper while she was awarded “most unusual sense of humour”.

“This game celebrates everyone’s differences,” she says. “Often in life, you want to be safely in the middle due to our judgmental society, but the rankings reward authenticity – to be at one extreme is a good thing.”

To play my game properly, rankings must never be about “most” or “best”, and you can avoid insulting people by putting yourself top or bottom of the most contentious ones (although it is true that I am the Friend most likely to get a UTI because they don’t dare ask a stranger to watch their laptop in the café). The rankings aren’t really even about getting things right – they’re a way to open up a conversation and give someone the opportunity to share more about the small parts of their lives.

As adults, we still need to play. Rhaina Cohen, author of The Other Significant Others: Reimagining Life with Friendship at the Center, has written in the past about how adults should “waste time together” like children do in order to bond and make memories. Writing in The Atlantic, Cohen argued that adult social events can often feel stale compared to the strange and creative rituals and traditions we develop with friends as kids. “Our desire for playful connection doesn’t disappear after childhood,” she wrote. “To enjoy the rewards of play, you have to take risks, but adults are often too consumed by self-consciousness to run with someone’s silly idea, let alone suggest one.”

I suggested and ran with a silly idea – and I can now confidently say which of my friends listens to the most showtunes and also know how much my friend Mia’s thoughts spiral when her partner is slow to come back from the shop. Unlike Beth, she’s not really worried about dying, but losing her loved ones haunts her in these quiet moments. Of course, you can have these discussions with your friends without introducing arbitrary rankings – I don’t mean to make it sound like I’ve never had a conversation before – but the framework is, more than anything, an opportunity.

The rankings have now spread from friend group to friend group and I am endlessly pleased by the increasing numbers taking part.

“It’s a game that cuts to the core of what’s so wonderful about friendship: someone knowing about, and caring about, your preferences and beliefs – deep and frivolous,” says one of my pals with whom I’ve been playing the game for months. “When we’re playing at ranking, what we’re really doing is saying, ‘I see you.’” Unexpectedly, the game has allowed us to go deeper into each other’s worlds than ever before.

Rules of the ranking game

• Pick an arbitrary, insignificant category – never rank friends on how hot they are or how much money you think they make.

• List everyone’s names in order, from most to least, eg: “Friends ranked by how much they spend on snacks at the cinema: Claire, Lauren, Tim, Bert.”

• Discuss and debate.

• Only rank people who are present and taking part in the game – do not rank others when they are not around.

Names have been changed, obviously!