Here's the prime minister for his second appearance in this year's top ten. This one took place in the heat of PMQs. The weekly bearpit can be a place for sudden flashes of temper, but it was the cruel mockery deployed by Cameron against Labour backbencher Michael Meacher which made this gaffe so unpleasant.
Meacher had used his question to point out to Cameron that Britain wasn't getting much inward investment - in fact, he suggested, it was getting less than Guatemala or Mali. This was the moment Cameron chose to insert a joke about former Co-Op chairman Paul Flowers, who had been suspended from the Labour party for buying drugs. The PM, in classic Eton school-bully mode, responded by suggesting the "mind-altering substances have taken effect".
Meacher wasn't happy, and complained about it on the floor of the House at the end of the session. Cameron had little choice, rather embarrassingly, but to say sorry - but not in a very convincing way.
"I completely respect the honourable gentleman. I made a light-hearted remark. If it caused any offence I quite happily withdraw it," he said. Not much credit to the PM with that one.