It's only in the last month or so that I've started wishing my index finger was sharper. More pen-like. My rounded fingertip is absolutely the wrong tool to shade in the necessary scalp stubble for a realistic portrait of Britney Spears. It is useless at painting "dubstep". And I know it does its best, that it never dreamed it would arrive in 2012 and suddenly be expected to be a Biro on top of everything else, but that doesn't stop me from looking over, covetously, at the middle finger of the aye-aye lemur, a finger that has evolved for foraging from holes, a finger that, when pointed at you, is believed by the Sakalava people to condemn you to death. The aye-aye, with its powerful digit, would be amazing at Draw Something. That's how I think now.

You've heard of Draw Something, surely. It's a sort of Pictionary for your phone. When you guess someone else's drawing, you both get points. If you're not playing it right now, one eye on this page, the other watching an opponent guess the meaning of your rendering of "wedgie", drawn out for them in real-time, then it's highly likely the person next to you is. Draw Something was downloaded 50m times in 50 days, making it the "fastest growing" mobile game ever. This second, around 3,000 pictures are being drawn there, 3,000 people hunched over their phone or iPad, tongue clenched between teeth, missing their stop on the 205, or ignoring a Power Point presentation on health and safety in the workplace, or yelling for their flatmate to come and see their lol drawing of Jordan. And I think its success says something lovely about us.

My mum thinks David Hockney is responsible for a spike in iPad sales among the middle-class middle-aged, those who are crowding into today's over-booked exhibitions, and not just for a sit down in the café. We love art at the moment, which might be one of the reasons why we're enjoying making our own, however basic. But the real thing about Draw Something is that it makes you like your friends even more. There is joy in watching the point they excitedly guess your drawing of Tina Fey when you add the glasses, and then more joy in watching them misspell Tina Fey again and again, imagining their frustrated little brow and their stubborn finger jabbing at the screen. "Tina Fay". "Tina Fei". "TINA FEY".

And as an insight into the way their funny broken brain works, watching how they choose to represent the word "helmet" with a limited colour palette is unsurpassable. The better you know them, the more likely you are to understand their drawings from the rough signifiers they offer. Also sometimes your friends draw penises. And spell out "poo" for a laugh.

David Ko, from the company that has just bought Draw Something for $200m, says the things that we want now, rather than "games" are "social apps". "People are busy. They want quick ways to keep in touch," he says. "Maybe you don't have time to call, but if you are playing together, to me it feels more social. I have lots of friends I keep in touch with on Facebook, but when I do this one-to-one thing with Draw Something, it feels a little bit more special."

It makes you like your friends more because you're both in it together. There is no competitive element to this game – no timer rushing your hand. No benefit to tricking your opponent, or choosing words they might not guess. It's nice. And because you know they'll be watching your brush strokes, including the bit where you choose the wrong nib size by accident and your world collapses around you, it feels like they are sitting there next to you, cheering you on.

I'm with Ko. The image of me and my friends spread over the world, doodling like children on a massive paper tablecloth makes me feel quite high.