Shadow chancellor Ed Balls is "the most annoying person in modern politics", according to the prime minister.
In a spontaneous outburst of annoyance during prime minister's questions, Mr Cameron interrupted his response to an MP so he could chastise Mr Balls for talking over him.
"I wish the shadow chancellor would occasionally shut up and listen to the answer," he said.
The Tory backbenches hooted with laugher, while Mr Balls smiled and reached across the despatch box to offer Mr Cameron a glass of water.
"I may be alone in finding him the most annoying person in modern politics," Mr Cameron continued.
"I've got a feeling the leader of the opposition will one day agree with me."
The exchanges marked a colourful session of prime minister's questions, which saw Mr Cameron ridicule Labour leader Ed Miliband's speech at the TUC march, when he compared protesters to the civil rights movement, the suffragettes and the struggle against apartheid.
"I know Martin Luther King had a dream, but I think it's time the honourable gentleman woke up," the prime minister retorted.
He later dismissed comparisons to the suffragettes as "absolute nonsense".
Mr Miliband largely confined his questions to frontline policing and university tuition fees. He attacked the coalition's cuts to police funding and condemned the government's response to growing number of universities set to charge the upper limit of £9,000 fees.
There was a lighter exchange between the two men when the prime minister congratulated the Labour leader on his upcoming wedding to long-time partner Justine Thornton.
Mr Miliband asked the prime minister for advice on stag nights, but the prime minister retorted that the Labour leader should look forward to the honeymoon.
"I would have done anything to get a honeymoon as leader of the opposition and I'm sure he feels the same way," the prime minister said.
The prime minister also faced questions over arming Libyan rebels, which he refused to rule out.
UK Uncut - the direct action group who occupied upmarket retailer Fortnum and Mason during Saturday's protest - came under criticism from Mr Cameron, who condemned their refusal to dismiss the violent scenes at the march.
The prime minister also criticised Labour MPs who signed an early day motion in support of the group.