When Wes Metcalfe bought a cucumber from a Tesco shop in Dinnington, South Yorkshire, he did not expect it to come with a dead worm.
So put off was he by the creature wedged inside the packaging, that he turned to Facebook to let Tesco know why it would be a while before he tucked into another cucumber sandwich again.
Tesco's comical comeback and Mr Metcalfe's response to it have gone viral.
It started on Saturday, when he posted: "Dear Tesco, yesterday I purchased one of your fine cucumbers to make my favourite dish - a cucumber sandwich.
"Upon opening my cucumber, I discovered a worm inside the wrapping.
"I thought - at last, finally Tesco have come up with something to beat Aldi's free-spider-with-bananas offer.
"I excitedly shouted the kids downstairs to come and meet our new pet.
"We decided to name him William.
"Our new pet appeared to be very unresponsive, we just put it down to him being sleepy and decided to give him some time to come round.
"Twenty-four hours later and William still hasn't moved - on closer inspection he seems quite flat (again, see picture) and I think he may be dead.
"Well... I'm no vet, but I think the tight shrink wrap on the cucumber may have squashed and killed William.
"I know Aldi's banana spiders were deadly, but at least they had some life in them.
"I now have three very upset children, a worm funeral to plan and to top it all off I've totally lost my taste for cucumber sandwiches, which as everyone knows are a favourite at any wake.
"So come on Tesco, wiggle your way out of this one."
An ode to William
Tesco's equally tongue-in-cheek response began: "I'll be heading to a muddy festival shortly, trawling through the fields of damp grass and dirt much like William would've during his happier times.
"This means I wont be able to make it on the day unfortunately, though I've decided to compose a poem, which I hope you can read out on the day.
"Would that be OK?
"Here goes: 'An ode to William.
Although life takes funny turns, we can all learn from William the worm.
Let us gather, light a candle to burn, and celebrate the life of William the worm.
Lights shine bright, let's eat sponge cake through the night! Because there's many a lesson to learn.
He wriggles many miles; he gave us many smiles, so we stand confident and firm...
William will be back, very much like Arnie, though now we will all check before we make a sarnie!'
"Wishing you the best, Rob - customer care."
So moved was Mr Metcalfe by Tesco's tribute, he shared a picture of William the worm's grave, with the post: "Funeral update: well what can I say? It's been an emotional day, but the funeral went without a hitch.
"Tesco Rob, we read out your poem, and there wasn't a dry eye amongst us.
"Keeping on with the poem theme, here's another, which I think sums up today quite nicely.
"#RIPWilliam #justiceforwilliam #poemsforwilliam.
As we gather here today for William the worm,
It's time to reflect on the lessons we can learn.
Now, this poor worm's life was cut far too short,
After he was crushed to death in a cucumber I bought.
Tesco, please don't let this happen again.
Don't let William's life be lost in vain.
But let's not focus on who's to blame.
Tesco have apologised admitting their shame.
As we resume William's body into the mud,
Please don't shed a tear. Instead, think of the good,
For William's death has brought us all here,
Sharing jokes and spreading cheer.
Before his death, William was completely unknown,
Spending his days in the mud on his own.
But now his name has travelled wide and far,
William the worm - the viral superstar!
The conversation did not end there.
The Facebook conversation has been shared more than 30,000 times and has had more than 10,000 comments since being posted on Saturday.
Mr Metcalfe, a trainee electrician from Sheffield, told BBC News: "I enjoy making people laugh, but you just can't tell what will go viral.
"I think it went crazy because Tesco's responses were so good.
"If they hadn't replied in such a fun way, then it probably wouldn't have gone so big on the internet.
"I've had a mostly positive response, but one lady didn't get the joke and told me off for making a fuss about the worm."
Mr Metcalfe said Tesco had offered him a £10 gift voucher to cover the cost of William the worm's funeral.
"I think Tesco have more than made up for it," he said.
"If people can laugh about it all, then that is great,
"There is enough seriousness in the world."
Mr Metcalfe also confirmed he would start eating cucumber sandwiches again.