Not showing the groom or even the guests the wedding dress before the big day is a time-honoured tradition.
But one bride-to-be has revealed how her own bridesmaid ruined the surprise reveal of her perfect gown by posting a picture of her wearing it on Facebook - and tagging her fiancé.
Sharing the shocking news on Mumsnet, the woman, thought to be from the UK, explained how she was left feeling "gutted" by her pal's actions.
Dozens of people replied saying she should be angry with her friend, with some saying they would 'sack the bridesmaid' over the inconsiderate post.
In her post the woman explained that she didn't think she would ever find "the one" dress as she's "very body conscious and anxious" but was happy with her choice.
She explained: "I went back for final fitting at the weekend and took one of my bridesmaids as she wanted to see.
"After finishing the appointment and getting home I saw that she had posted a photo of me in the dress on Facebook (during the appointment so it had already been on an hour or two when I saw it)."
The bride-to-be went on to explain how her partner had been tagged in the post and her friend had written: "She bets he couldn't wait to marry me and how lovely my dress is."
However, when she asked her friend to remove the picture the friend acted as if it wasn't important.
She said: "When I asked her to remove it her response was 'it doesn't matter if he's seen it he's a man so he will have forgotten what it looks like in five minutes time'.
"My dad had also seen it as well and it was going to be a surprise for him on the day too.
"I just don't know what to do or how to feel! I am so gutted that it now won't be a surprise to my partner or my dad.
"She knew how much that meant to me and the only thing I had asked for was that details of how I will look on the day were kept a surprise from my dad and partner.
"As I paid in installments the dress is now fully paid for and I don't have time to get another one and do all the alterations etc. Someone tell me I will stop feeling like this soon!"
Dozens of people responded to the post and said the bride-to-be was right to feel so disappointed.
One person said: 'I would be furious! I'd be seriously considering if she would be coming to the wedding!'
And another agreed and said: "Sack the bridesmaid! Don't worry, your dress will look different when your hair and make-up are done etc. Try not to let it spoil the day."
Others agreed with "sacking" the bridesmaid and not giving the woman a part in the wedding.
Someone else said: "I would be angry at that one. You don't share pictures of someone else's wedding dress before the wedding!"
While one person said they would be "furious" and even called the bridesmaid a "b***h".
They said: "She's a massive b***h or a complete idiot. I'd be furious and you are not unreasonable in the slightest!"
Someone else tried to reassure the woman, but agreed the bridesmaid didn't seem like a good friend.
They wrote: "It doesn't matter in the long run. But how devastated you must feel. I don't think she sounds like much of a friend, personally."