The teen begged her parents for the cute piglet and the family, from Glasgow, travelled down to England to buy him.
However, three months later he was given to an animal sanctuary.
He now weighs 20 stone, twice the weight of a healthy adult, and is 1.2m long.
The giant hog is now living in a three-bedroom house after getting used to creature comforts with his old owners.
Morag Sangster from Edinburgh and husband John Ryan founded Tribe Sanctuary in Carluke, South Lanarkshire, and have four 'failed micropigs' in their care as well as more than 100 animals.
Francisco is the only pig who lives in the house, after arriving during a cold winter three years ago - and hating snow when he was sent out.
Morag, who works as a tattoo artist in Edinburgh and Glasgow, lets Francisco live in the house where the giant hog enjoys chilling in front of the fire while she sits on the sofa.
Franscico roams around upstairs, and likes to spend time in the kitchen.
Fraudsters flogging 'micropigs' to duped families can make a profit of more than £700 - which Morag believes happened to Francisco.
Morag said: "Francisco was three months old when he got here and he was around a foot long, now he weighs 20 stone.
"He's not micro at all.
"Having a pig in the house is quite fun, but not for people who cherish their furniture.
"He has bitten a few things and he loves to scratch, we have given him a blanket.
"Standards go out the window - he goes wherever he wants.
"He goes in the garden and goes to see the neighbours.
"Somebody went down to England to pick him up, a 15-year-old girl wanted a micropig and they paid a lot of money, she found him on Instagram.
"He was only allowed in the girl's bedroom and the hallway, then he had a tiny pen in the garden.
"He started crying a lot and the family said it was 'undesirable behaviour' he was exhibiting.
"It is a big con, a big porky."
Francisco arrived during a snowy winter three years ago, and was taken into the house because he had been used to being in his previous owner's bedroom.
Morag said: "When he arrived he had been used to spending the night in the girl's bedroom.
"It was winter and really cold, we put him in the living room on a blanket.
"It started snowing and he didn't like it at all, he has short legs and his belly was touching the snow and he ran back in the house.
"Pigs are really clever - they are cleverer than dogs and easy to train."
Francisco sleeps on a futon in a spare bedroom with the couple's four dogs, and usually one of them will cuddle up with him.
The pampered pig enjoys being in front of the fire or near a radiator, and has his own duvets and quilts.
Every morning he has a banana for breakfast, and also likes grapes and nuts and chewing on straw and hay, and is fed in the conservatory away from the dogs.
He eats special potbellied pig pet food which costs £15 for 15kg, rather than standard pig food which would cause him to gain weight, and has lots of fruit and vegetables.
Morag, from Edinburgh, said: "He's got his own quilts and duvets.
"He can't get up on the settee as much as he would like it, because pigs can't jump.
"He loves lying in front of the fire, I could put my feet on him if he was in front of the telly and gave him a belly rub.
"He sleeps on a futon which is an extra large dog bed supposed to be indestructible.
"He and the dogs sleep in the spare bedroom, he goes into his bed and one of them will jump in with him.
"It is great having a big kitchen as pigs are not nimble, it is like a five-point turn for him to move around.
"He is quite chatty, he grunts and squeaks - he is as rewarding as any cat or dog.
"They are clean animals, he doesn't go to the toilet in the house."
She said the trade in micropigs was 'deceptive with consequences which can be cruel'.
All the six other pigs - including Elvis, also bought as a 'micropig', who weighs 31 stone, and Max and Vera, former micropigs who were given up - live in stables.
Morag believes the 'giant porky' being peddled to well-intentioned punters is a cruel con.
She said: "Around 50 'micropigs' a month are given up as they are actually piglets.
"A small piglet will cost between £25 and £40, but a micropig can cost around £800.
"It is wishful thinking, these people will cash in if people believe what they are telling them.
"If they think people are stupid enough to believe it, they willl sell them.
"It's a big problem.
"There is no such thing as a 'micropig' breed.
"There is a piglet or a smallish pig.
"It is an animal welfare problem.
"There is no rehoming market for pigs, I'm sure a lot of them end up at the slaughterhouse.
"There are no rules for pigs being sold newborn, you can do what you want with pigs.
"People have them in the house because they are cute."
For 30 years Morag, who is vegan, dreamed of opening a rescue centre.
She added: "Last lockdown we got a lot of orphaned lambs because farmers were selling them for 'lockdown entertainment'.
"It is shocking.
"We haven't seen an increase in rehoming in lockdown but we will find the fallout after lockdown."