PMQs was a case of 'my brain is bigger than your brain', inspired by Red Ed's earlier bold assertion that he had "more intellectual self-confidence" than Blue Dave. A button had been pushed.
After seeking to duff up the PM on rent controls, the chief comrade lasered in on American drugs giant Pfizer's not insubstantial plan, £63 billion, to gobble up the UK's pharmaceutical firm AstraZeneca.
Labour having narrowed the public interest test, now, post-Kraft/Cadbury, want it widened again to include major drugs companies. Ed spoke of deep public concern at Pfizer's proposal and asked about what type of intervention the Coalition was considering.
As the pink mist reddened, Blue Dave eyed the Labour leader and accused him of "playing politics rather than backing the national interest".
After Red Ed called for a "proper assessment" of the bid - which hasn't actually been made - the PM insisted he would judge any proposal on whether it expanded British jobs and science.
And then, he responded to the chief comrade's jibe about being more self-confident, telling MPs to cheers: "Of course, he's extremely clever and we all know that."
But the self-confident Labour leader kept on. He warned Blue Dave if the bid went through without a proper assessment like a public interest test, then the PM would be seen as a "cheerleader" for Pfizer.
The pink mist turned into a crimson tide that slowly rose and deepened until the PM's head was a nice shade of puce.
"It is deeply sad," intoned Flashman, "that the leader of the Opposition makes accusations about cheerleading when the Government was getting stuck in to help British science, British investment and British jobs."
Later, the PM, once again, got stuck into the Speaker. As former rail minister Simon Burns was called to ask a question in injury time at 12.33pm, Mr Cameron could not resist a dig at the referee.
After being cut off in mid-flow last week by the Speaker, the PM told Mr Burns that to be called so late showed "if you stick at anything you can win".
Moments later, Dave's aide, questioned by hacks insisted his boss and Mr Bercow had a "very good working relationship". He then issued a big grin and said: "Next?",