First rule of politics: Don't mock those who elect you.
Second rule: Especially when you're on camera.
Third rule: Especially not grandmothers.
Australia's Prime Minister Tony Abbott is not having a good week.
The woman, who's a grandmother, called in to ask the prime minister how she was expected to survive financially in the wake of tax increases and cuts to public services.
She told him she worked on an adult sex phone line to try and make ends meet.
At this point Mr Abbott can be seen winking at the ABC host, smirking and trying to suppress a laugh.
He then appears to glance over at an adviser and quickly tries to adopt a more concerned expression.
It doesn't look great.
I've written before that sometimes Mr Abbott's so-called 'gaffes' may actually in fact be calculated to add to his "blokey" appeal.
But in a week where he's already been heavily under fire, I suspect this wasn't the case this time.
His Treasurer Joe Hockey has already come across as arrogant in the eyes of many.
First: when he was caught smoking Cuban cigars in the days before delivering his "age of entitlement is over" budget.
And secondly: when it emerged Mr Hockey had danced to the song "This Is The Best Day of My Life" just moments before announcing thousands of job cuts.
Today the prime minister cancelled a visit to Deakin University in Geelong in anticipation of protests from students angry at the budget.
Foreign Minister Julie Bishop was roughed up at a similar university visit last week.
In the eyes of many voters, politicians are already seen to be taking the mickey, without doing so explicitly, on camera, to a grandmother.
One wonders what Malcolm Tucker, the potty-mouthed spin-doctor from the brilliant British series The Thick of It would have made of it. I suspect there would be some pretty strong language.