She also went as far to say that the mother should have consulted her before naming the child.
Taking to popular mum forum Mumsnet, the unnamed woman asked if she was being unreasonable.
In the original post she wrote: ‘The first name she came up with was Joseph, it’s a nice name, but I said I thought she might of [sic] gone for something a bit less mainstream.’
The parents listened to her advice and opted for a different name by calling their son Sonny instead.
One user wrote: ‘Are you having a laugh? What your sister calls her child has f**k all to do with you.’
Another user told her to keep her nose out of it: ‘Minding your own business is the way to go.’
One hilarious response by a sarcastic user read: ‘Omg hun, I can't believe she would do that. Obviously she was supposed to present you with her top 3 choices and have you vet them all. How selfish and inconsiderate of her to pluck a name out of thin air and expect you to just deal with it!!
Some even questioned the authenticity of the question and believed it may have been a reverse query from the mother herself. She may have been seeking merit for being upset that her sister demanded naming rights.
The controversial post has since been deleted from the forum.