Matt Chorley: Whatever it is, the over-enthusiast is right behind it

It is a bumper season for over-enthusiasts. Their deckchair-pocked buttocks have barely recovered from sleeping out on The Mall when along comes another jamboree of flags, snacks and trivia.

There are those who will enjoy the Euro 2012 tournament, and there are those who will be seen to enjoy it. The latter will have very little idea what is going on, but will have relentless optimism that everything – everything – to do with the tournament is fascinating, from the exact loop of touchline video advertisements to Clive Tyldesley's pronunciation of Ukrainian towns.

The figurehead for this bout of witless puppy-dog enthusiasm is our very own prime minister. David Cameron purports to be an Aston Villa fan. As do I. I'd be amazed if our collective knowledge stretched beyond the Dean Saunders and Gareth Southgate Pirelli stickers I collected at school.

Being a diehard Villa fan in no way stopped the PM punching the air at Camp David when Chelsea won the Champions League. This is not a criticism. Better to get carried away with bottled beer and Doritos than the nuclear launch codes. But sometimes he goes a bit too far.

Take his good luck message to Roy Hodgson and the England squad. "The whole country is behind you, and will be cheering you on...". But then he had to ruin it: "... hoping that you can do what no England team has done for nearly 50 years, and win an international trophy". Surely, at this point, Sir Humphrey should have stepped in and said: "Don't be daft, Prime Minister."

Still, Cameron is not alone. With a major football tournament under way, thousands of us will suddenly take an intense interest in what we'll irritatingly refer to as "association football". One minute we think John Terry makes chocolate oranges, the next, our pint of Carling is smudging our St George's face paint, as we wonder aloud if Boris Becker is still involved in the German coaching set-up.

Recent football converts are easy to spot. They are the only people wearing the new England strip. It will be tucked in, to allow swift access to their Blackberry holster. Plastic flags fluttering on car roofs are a warning sign that the occupants will wind down their window to explain the newly learned off-side rule to anyone who'll listen.

They will buy "a beer fridge". They will religiously fill out wall planners – at least until England's second game. They will collar colleagues at work urinals to discuss "the game".

They absorb facts like the commemorative Euro-sponge they picked up from the Texaco garage. There will be long, fatuous debates about tactics. There will be long, long, long fatuous debates about formations: 4-4-2 or 4-3-3 or 4-3-2-1 or Diamond or Christmas Tree or Pinecone.

But you cannot fault their enthusiasm. Be happy for them. Be happy for us.

It will only last until 1 July. And then we can start swotting up on Argentina's decathlon Olympic hopefuls.