Visit any Catalan home at Christmas and you will find what appears to be an interloper hiding among the traditional figures around the crib in the nativity scene.

Joseph and Mary will be in pride of place around the manger gazing adoringly at baby Jesus. The three Kings will likely be in attendance, along with a group of shepherds and a set of traditional farmyard animals.

But look closer and you will spy a figure squatting with pants down, bare bottom raised over a little brown pile of poo – glance up at the face and chances are it’s a figure you recognise.

Some families like to use the same figure year after year, often a character that has been passed down through the generations, and quite likely the traditional Catalan figure of a young peasant dressed in white sporting a red barretina and a pipe.

But there is a growing trend to purchase a new figure each year – a trend that is proving profitable for a handful of artisans who produce the figures each year.

Politicians always prove popular, so too do sporting heroes.

Cartoon characters, literary figures, film icons can all be found on the shelves of stalls selling caganers.

In fact, the models don’t have to represent animate things at all.

One of the best sellers for 2018 is a figure depicting the yellow ribbon that has come to represent the political prisoners currently behind bars in Catalonia for their roles in pushing Catalonia towards independence.

This year’s bestsellers include Carles Puigdemont, the ousted regional president of Catalonia who fled into exile in Belgium when a warrant was issued for his arrest after he unilaterally declared independence for the region in October 2017.

Freddie Mercury is proving a hit this year, presumably riding the success of the biopic Bohemian Rhapsody.

Montserrat Caballe, his partner in the famous duet Barcelona is also a surprise hit this year. The Catalan soprano who died earlier this year will be the star of many a nativity scene this Christmas.

Theresa May appears as a caganer this year, but sadly, as at home in the UK she is not proving too popular.

While you might think that being immortalized in clay with your bum cheeks on display is not a desired status symbol, it is considered an honour to be chosen as a caganer.

“The caganer is a well loved and respected figure in the typical Catalan Nativity scene,” one of the largest caganer producers state on their website.

“It is not making fun but quite the opposite, it is a tribute to the person and the office or activity they represent.”

Their appearance in nativity are thought to date back to the mid-18th century when they were placed behind the stable scene to symbolize fertilization, and bring luck and prosperity for the year ahead – as well as a fruitful harvest.

Catalonia’s obsession with defecating at Christmas goes beyond the caganer figures.

Also look out for wooden logs with painted faces known as Tió de Nadal, a jolly Christmas log which they stick in the fireplace every Christmas Eve.

Tradition says you must order Tío Nadal to defecate while spanking him with a stick. The ever-smiling tree trunk then waits for all the kids to go to bed before crapping their presents.

READ MORE: 12 weird and wonderful Christmas traditions celebrated across Spain