After spending a modest £26.45 on a meal for two, the prime minister didn't even leave a tip - only hours after pledging to help low-paid workers.
On the same day Cameron gave his closing speech at the packed Conservative conference promising to cut taxes to more than 1 million people working on minimum wage and a tax cut to 30 million more.
David and Samantha wait their turn
Restaurant manager, Joshua Coelho, 23 went that little bit further whilst serving the Cameron's.
He said: "We don't usually do table service but I thought I would make an exception for the prime minister. He didn't leave a tip but we didn't really care."
The fast food restaurant chain, recommend by Barack Obama, pays its employees £6.50 per hour. It is to these working class people, Cameron pledged to help.
Restaurant managers are on a slightly higher wage of around £19,000 per annum. A price of a burger starts at £3.75.
However, some people are claiming Cameron was correct to not leave some extra change.
If re-elected next year, the Tory leader aims to increase the income free tax amount to £12,500 from £10,500. This would mean that those working a 30 hour week on minimum wage would pay "nothing. Zero. Zilch" in income tax.
He also promised to raise the 40p tax threshold from £41,900 to £50,000, which would in effect help thousands of middle-income earners.
Service charge in Five Guys is not added to the final bill so if one is to tip, it is at the discretion of the customer.
Dave does have a bit of past form with tipping - in 2011 he got into hot water for not leaving anything for a waitress in Italy and had to return to make amends.
But, to be fair, he did leave a fairly whopping tip in a pizza restaurant last year.
As Cameron stated Wednesday: "We say you should keep more of your own money to spend as you choose."