The whole idea of a gender reveal is to surprise everyone - in unison - about the sex of the baby who will soon be welcomed to the world.
But unfortunately for this expectant mum, a Card Factory worker accidentally let the cat out of the bag while she was purchasing some items for the upcoming party.
Jess Gildenhuys said that she found out whether she'd be having a boy or a girl in the 'worst way ever' in the wake of the shop blunder last month.
The 33-year-old, from Norfolk, was browsing the aisles in Card Factory fresh from her 20-week ultrasound scan that had taken place that morning.
While she was admiring the greeting cards and gifts as she picked up a birthday card for her mum, Jess and her husband Josh, also 33, then spotted the firm's gender reveal range.
There were confetti cannons and balloons on sale which she thought would be perfect for the occasion, as she was planning on hosting a party to reveal the sex of her new child with her nearest and dearest.
Jess and Josh Gildenhuys found out the sex of their unborn child at a Card Factory till (Kennedy News and Media) Jess explained that the doctor she had seen earlier that day had jotted down the sex of the baby and sealed it in an envelope, admitting that her and her hubby had found it 'painful' not to take a peek.
But she was keen to find out the news as a family, so she checked with staff about whether they'd be able to help facilitate the surprise.
The business owner, who runs Hello Moon Crystals, claimed that a Card Factory employee told her they'd be able to keep the secret safe by removing the labels on the cannons to prevent the parents from prematurely finding out.
So far, so good - but when she was paying for her items, Jess was left gutted when the description of the products flashed up on the till and completely gave the game away.
While fumbling for her purse in the Card Factory queue, she and Josh couldn't close their eyes quick enough when the words 'coastal blue' came up on the screen.
And to add salt to the wound, this was also printed on her receipt - so the couple's plans of surprising themselves as well as their loved ones at the gender reveal were scuppered.
Take a look at this:
Needless to say, the soon to be mum-of-three was left feeling pretty miffed that she was unable to share this special moment with her two daughters Jupiter, six, and Athena, three.
"It's the worst way ever to find out the gender of your baby, you couldn't even write it," Jess fumed. "You absolutely do not expect your gender reveal to be inside a Card Factory.
"I was so shocked. It's hard to be shocked in that situation and keep your cool when you're in a public place. I didn't want to make a big deal of anything.
"It was disappointing because we didn't find out as a family, but it's also a funny story to tell, I guess. I mean what can you do in that situation apart from just laugh about it?"
The mum sent an email to Card Factory a few days later to explain her frustrations about the surprise being spoiled, with the firm offering their 'sincere apologies' for the mishap.
Jess and Josh went ahead with their plans to host the gender reveal - even though the element of surprise had been thwarted for them - as they still wanted to celebrate with their loved ones.
The soon to be mum-of-three said it was the 'worst way ever' to find out the gender (Kennedy News and Media) "Because this is our last baby for sure, we wanted to make things a bit more fun and do something as a family," the mum said.
"It was disappointing the way we found out. It was ruined in that way. At least it made it fun for everyone else. At least it wasn't just me, at least I was with my husband.
"I didn't want to say anything to the person at the time either because I didn't want to come across rude or disrespectful or anything.
"I just can't believe I'm going to be a boy mum. I'm like, 'oh my god!' It's exciting though, It'll be fun I'm sure."
She shared a video on TikTok about the incident, captioning the clip: "@CardFactoryUK ruining our gender surprise."
A spokesperson for Card Factory said in response to the incident: "We've been in touch with Jessica to offer our sincere apologies.
But the couple still hosted the gender reveal to celebrate with the rest of their family (Kennedy News and Media) "We've also issued reminders to our teams to advise customers that these items can show up on our till screens and receipts.
"We would like to try help make amends to Jessica and her family and encourage her to make contact with our customer service team."
A lot of social media users pointed out it seemed like an innocent case of human error, while some even admitted they would have probably made a similar oversight while behind the till.
One said: "You can't blame them they've simply scanned the barcode not realising it would come up as blue or pink."
Another wrote: "Oh dear haha. Maybe next time get a friend or family member to get the items."
A third commented: "Imagine finding out in Card Factory."
And a fourth sarcastically said: "You poor thing. I can't imagine going through such a thing in my whole life. Sending so much sympathy to you and your family."