Name: The girther movement

Age: One day old.

Appearance: Questioning, sceptical, suspicious.

Is it like the birther movement, but for ventriloquists? No, it is like the birther movement, but for Donald Trump’s weight.

What are its chief aims? There is just one: to promote the theory that Donald Trump is fatter than the White House says he is.

Sounds good. Where do I sign up? Don’t worry – if you’ve got a Twitter account, you are in.

How did it start? The term “girther” – an obvious play on “birther”, the common name for someone who, like Trump, maintained that Barack Obama was born in Kenya – was coined by MSNBC’s Chris Hayes on Tuesday.

Why? Because that was the day that Trump underwent his first physical examination as president, and was found to be in great physical shape.

Did the doctor perform the examination blindfolded? OK, Trump’s in “excellent health” for a 71-year-old man who takes no exercise and subsists largely on a diet of fast food eaten in bed.

How can this be? White House physician Dr Ronny Jackson put it down to “incredible genes”. That said, at 6ft 3in (1.91m) and 17st 1lb (108kg), with a Body Mass Index of 29.9, Trump is overweight, and three pounds heavier than he was in 2016.

What is there for the girther movement to question in that assessment? For one thing, they have been comparing Trump’s physique with that of various top athletes who are the same weight and height. In every case, the resemblance is less than striking.

That’s probably because he goes everywhere by helicopter and golf cart, like an entitled slug. For another, Trump’s New York driving licence says he is only 6ft 2in.

What’s an inch? Were Trump but an inch shorter or a pound heavier, he would officially be classified as obese.

Conspiracy! Is the doctor in on it? It seems unlikely. Dr Jackson was Obama’s White House physician.

Did he check Trump’s mental capacity? Yes. Trump scored 30 out of 30 on the Montreal Cognitive Assessment test.

Stable genius! Not really – it’s just naming animals, drawing hands on clocks, that sort of thing – but it probably means he doesn’t have incipient dementia.

Do say: “I think we need to take this firther.”

Don’t say: “Technically it’s a rhinoceros, but ‘pointy horse’ will do, Mr President.”