Posting on behalf of a friend who is unsure how to deal with this.
Friend is getting married this summer and is wearing a traditional white floor length wedding dress with veil. Wedding is very small with 19 guests, all immediate family. MIL has just sent her a picture of a floor length white dress which she intends to wear. How does friend respond?
Two choices - get STBDH to deal with it, or reply "haha, I thought you were serious!"