Labour leader Ed Miliband is the latest in a long line of politicians to be caught out when it comes to the costs of everyday items.
David Cameron and Chancellor George Osborne came under fire from one of their own backbenchers, Nadine Dorries, in 2012 when she described them as ''two posh boys who don't know the price of milk''.
The Prime Minister said the claims were "nonsense", later putting the cost at "just under 50p" and insisting he did "a lot of the family shopping".
But Mr Cameron was tripped up last year on the price of budget supermarket bread, suggesting it was ''well north of a pound'' when at the time it was around 47p.
''I don't buy the value sliced loaf - I've got a breadmaker at home which I delight in using and it turns out in all sorts of different ways,'' he explained.
London Mayor Boris Johnson failed the milk test last year, suggesting it cost "about 80p or something like that".
When told by BBC presenter Jeremy Paxman it was around half that, he replied: "Well, there you go, I don't know how much a pint of milk costs. So what?"
In 2012, Jim Paice, then farming minister, admitted he did not know the price of milk because ''my wife buys most of it''. His comments were particularly embarrassing because they were made as dairy farmers planned to protest over milk price cuts.
Challenged by a caller to a local ITV news show about how much pensioners received and Mr Clegg said he thought it was ''about 30 quid now''.
At the time the figure was £90.70 a week for a single person and £145.05 a week for a couple.