When it rings the temptation is to answer it quickly. When the traffic lights change before you can get through them you tend to think you can put your toe down, sneak through and it won't matter.
We all do it and on occasions like those you think: "Oh, it's only a few seconds." A few seconds never matter much to anyone, we think, and generally we're right. We get away with it so we do it again, like a private detective listening to other people's voicemails. It's only a little thing and no-one gets hurt, right?
But one time in a hundred there's someone else already in the junction, a cyclist is in your blind spot, someone pulls out ahead of you without looking. One time in a hundred you'll prang your car and get shaken up, and one time in maybe a thousand you'll kill yourself or someone else.
Jemma O'Sullivan was in a van with her boyfriend on the M18 near Doncaster when a lorry driver hit them from behind, pushing them into another lorry which in turn hit a second van. Jemma, who was just 22, died. Her boyfriend had serious injuries, as did most of the other people involved.
Lorry driver Christopher Kane, who at 67 should have known better, was texting at the wheel. He admitted causing death by dangerous driving and has been sentenced to five years' jail.
A tragic tale, we might think while turning the page and going on to read about the X Factor. Sad but nothing to do with us.
Well, it is. Because we all do that, don't we? If we're honest.
I do. I have a hands-free kit to make and receive calls while I'm driving, but it's not always plugged in and sometimes I just answer the phone without thinking. I never text or check my emails unless I'm stuck in traffic, but many's the time I've had a quick glance and narrowly missed a 2mph shunt in a traffic jam.
And I don't have any excuse for it. Generally I'm driving around for work but there's not much that can't wait half an hour, or that I couldn't pull over to deal with before driving on. But then we all forget when we're in our cars that they are massive metal boxes moving at speed, and that humans are squishy and do not come with crumple-zones.
None of us have any excuse for it. Every single mobile phone these days comes with a free - A FREE - earpiece so that calls can be answered safely when the user is behind the wheel. Yet I see half a dozen people every day yabbering on a phone held to their ear while they have just one hand on the wheel and only half their mind on the road.
There were 31,035,791 cars on the UK roads last year. Roughly that number of new mobile phones are sold in this country every year. Each of them with a FREE earpiece, which means there is no excuse for every one of those drivers to have left it in the box.
At the same time there were 171,000 fixed penalty fines issued by police for driving while on the phone - equivalent to one every three minutes, and the figure is rising. The fines are rising too, from £60 to £100, but it still doesn't seem enough to stop anyone doing it.
Driving home from the pub while three sheets to the wind didn't use to matter, largely because the roads were empty and the metal boxes were slower. Over time as more people were killed by drivers' selfishness it became socially unacceptable, and to see someone leave a Christmas party tipsy and clutching their car keys today would provoke a wave of revulsion and criticism.
Yet driving while using your phone is more likely to cause an accident than driving drunk. Not one of us would think driving drunk is a good idea, but we all think there's not much harm in reading a text.
We're wrong. I'm wrong, you're wrong. If you're using your phone behind the wheel you're not trying to kill yourself and other people, but you are clearly not bothered if you wipe out two vans, a couple of lorries and a young kid just starting out in life.
If only there were a sticker you could put in your windscreen or on your bumper which says "I try not to kill other people." Unfortunately there isn't, but there are a load of cheap hands-free kits, there's common sense, and in case you haven't got the message yet there's a FREE EARPIECE IN THE BOX.
"HELLO? YEAH I'VE BEEN IN AN ACCIDENT..."