Mr Rudd has been labelled a ''phoney'' after he swore on a TV program about the financial crisis.

''People are going to run a huge scare campaign about government debt and government borrowing,'' Mr Rudd said, discussing the $42billion stimulus package.

''People have to understand that, because there's going to be the usual political shit storm, sorry, political storm over that.''

The self-described nerd has form. He went into ocker overload with the troops in Afghanistan before Christmas. He remarked about the ''genuinely shitty weather'' and told soldiers ''you really know your shit'' and ''you guys are bloody good''.

Author Peter van Onselen, who claimed last year that the Prime Minister often used the ''f-word'', said Mr Rudd would rapidly fill a swear jar for his language used behind closed doors.

''There are two Kevin Rudds. There is the Kevin Rudd that his staff gets to see and there is the Kevin Rudd that the Australian public voted for and they are very different.''

A number of workers who were sacked by Pacific Brands were in the TV show audience, which led critics to argue the moment was scripted.

Melbourne's Liberal Mayor Robert Doyle said Mr Rudd swore to sound ''human''. ''He usually gives a pretty robotic performance, so I'm sure that that was a clever little snare in there to make him sound like one of the lads.'' Federal Opposition frontbencher Peter Dutton said it showed Mr Rudd was a ''phoney''.

But one organisation hopes to cash in. Helen Connealy of the Schizophrenia Research Institute urged Mr Rudd to try to stop swearing for a week and raise money for research with any slip-ups.