Remember when David Cameron wondered during a radio interview if "too many tweets make a t**t"?

His suggestion was unintentionally obscene (and therefore unrepeatable) because he didn't know what the colloquialism really meant.

However, the prime minister is now a convert and has set a new parliamentary precedent by becoming the first person to introduce a tweet into Prime Minister's Questions.

One of his quick-thinking aides spotted that former Labour minister Tony McNulty had tweeted something less than flattering about Ed Miliband's performance during the weekly clash.

"Public desperate for PM in waiting who speaks for them - not leader of Opposition indulging in partisan Westminster Village knockabout," it said.

Within moments, Cameron had read out the 140-character assassination and broken new ground - and probably ended McNulty's hopes of finding a new Labour seat for the election.

Another former Labour minister, Michael Meacher, still sits in the Commons and was deeply upset when he asked a question of Cameron only to be told, in a reference to shamed Co-op boss Paul Flowers, that it sounded like he had been enjoying "mind-altering substances".

Meacher was mortified, demanded an apology for the "unjustifiable, rude and offensive phrase" - and got it. Sort of.

Cameron said: "I made a light-hearted remark. If it caused any offence I quite happily withdraw it." He added that he had been attempting some banter and it was important for the Commons to have a sense of humour.

"Meaning you, Meacher," is what he didn't quite say.

The law of unforeseen consequences operates in mysterious ways - by definition, really.

Deputy prime minister Nick Clegg recently announced a radical new green policy to force all supermarkets to charge customers for plastic carrier bags.

Sadly, it may not have quite the straightforward effect on the environment the government was hoping for.

Cardiff council introduced such a scheme two years ago, since when the number of shopping trolleys stolen and abandoned in the street, and presumably the river, has rocketed.

Attempts to suggest the relationship between Labour leader Ed Miliband and his shadow chancellor Ed Balls is as poisonous as the one between their predecessors Tony Blair and Gordon Brown didn't quite take off this week.

An internal email from the Miliband team suggesting that Balls' approach to briefings on the economy was a "nightmare" fell a bit short.

Perhaps worse, though, was the suggestion by Balls when questioned about their friendship that he had never been to the pub with Miliband.

"I've known Ed 20 years and I can't think that I've ever been... Different people like different places and I was last in the pub yesterday. I don't know if he likes the pub or not."

Somehow the idea of the two Eds boozing it up together in the Dog and Duck never really stacked up anyway. But it did start a Westminster village hunt for any pictures of Miliband caught in the act of visiting licensed premises.