Image copyright Twitter Image caption It's like a really weird game of Guess Who?

Have you heard the one about the sheep so big the CEO of Tesla made it his profile picture?

Elon Musk first tweeted the picture as a joke, but then went a step further by replacing his Twitter avatar with the image of the farmyard animal.

This did not sit right with the sheep photo's owners, the Museum of English Rural Life, which soon made a change of its own.

Now visitors to its Twitter page will be greeted with Musk's smiling face.

Image copyright @TheMERL

Musk is known for participating in running jokes and slang online, such as previously asking Twitter users for their "dankest memes" and releasing a rap song about Harambe, the gorilla shot dead in a US zoo who then became a social media touchstone.

And he has been enjoying his time as a sheep by replying to genuine Tesla car customers with oblique sheep puns to thank them for their purchases.

Likewise, the Museum of English Rural Life regularly joins in with internet humour, and has used its time as Musk to tweet jokes about "electric sheep called Teslewe".

Adam Koszary, Programme Manager and Digital Lead for Museums Partnership Reading, is the man behind the museum on Twitter.

"The end-game for our whole Twitter," he told the BBC, "is engaging people with English rural life, even if that means memes.

"We'll change our picture back either when Elon changes his back, or at the point where people are confused enough to show up to Elon Musk's house expecting it to be the Museum of English Rural Life."

The original sheep picture originates from the museum's archives, where it is described as a 1962 photo of an Exmoor Horn aged ram, taken in Devon.

It caught the attention of the internet in April 2018 when the museum, which is part of the University of Reading, shared the picture online alongside the caption "look at this absolute unit".

The phrase "absolute unit" is internet jargon, meaning a large, muscular person or thing.

It is regularly used as a compliment - for example, it has been used thousands of times online to describe both a shockingly muscular kangaroo and a giant steer who each made the news in 2018.

With regards to the ram, Dr Ollie Douglas, Curator of the Museum of English Rural Life Collections, revealed the secret behind its size.

"The breed was intended for meat and wool production," he wrote in a blog post. "In other words, it was the full package, or as our social media folks put it, 'an absolute unit'."

The museum has built itself a bit of a reputation for funny business online.

In January 2019 it started a war with fellow museums over who has the best duck in its archives, and in October 2018 it may have spawned a new JK Rowling character with a tweet about a chicken in trousers.

And in February 2019, meanwhile, the tweets in its thread of updates about a lost bat in its rare book store were liked more than 25,000 times.

The bat became so popular online that it was even awarded its own university library card.