Oh. A mother-in-law has decided to wear a "wedding dress" to her son's wedding.

Nope.

This is not a thing that should have happened.

You see, a bride just discovered her mother-in-law has big plans for her wedding.

More specifically, she wants to wear her very own “wedding dress” to said wedding.

The, erm, slightly miffed bride-to-be shared her story on Reddit under the username Iswo26.

“My MIL just bought a dress to wear at my wedding. She did ask me beforehand what type of dress I think she should wear. I specifically told her to find something that is navy blue, dark green or grey and something conservative,” she said.

She then went on to explain that her mother-in-law did the complete opposite of what she told her to do.

“It is gold with gold embellishments and gold threading. The whole dress is sparkly. When she showed it to me I was absolutely shocked and I wasn’t very happy with her choice of dress. My dress in comparison is very simple with a little lace and some satin,” she continued.

She included an image of the dress in her post:

The Reddit user said her mother-in-law was also planning to change into a second dress during the reception. This dress would be green, off-the-shoulder and covered in sequins.

"Can you believe this woman?" she asked the forum. "I honestly can’t brain any of this as she’s an extremely simple woman who doesn’t even put effort to dress up on normal days."

"I did tell her in the most diplomatic way possible that her dress is not suitable for the function. She grabbed the dress out of my hands, stuffed it in the cupboard and gave me the silent treatment," she added.

The people of Reddit overwhelmingly agreed with the bride that her mother-in-law's behaviour was a lil' bit odd.

"You are not rocking the boat," one person commented. "She is rocking the boat. You're not overreacting at all - that is a literal wedding dress right there. She asked you what you wanted and went and did the exact opposite."

"Totally inappropriate. I would tell her, that there is no wearing that dress at your wedding. Remind her of your guidelines and insist that she gets a dress in a suitable colour," added someone else.

"Time for a bottle of red wine in a large cup wielded by a good friend with lots of spine," another person suggested.

The bride-to-be later updated her post, saying she was planning to "tease" her mother-in-law about the dress until she got the not-so-subtle hint.

Do you think the mother-in-law's dress is inappropriate? Tell us about it in the comments below.

Want to help Mamamia with some new ideas? Plus go in the chance to win $50? Take our quick survey now.