The song performed by mum-of-four Juliet Moody, 36, with 31-year-old Catherine Crowley has struck a chord with half a million viewers on YouTube. Its lyrics include:
"Everybody knows new mothers are exhibitionists.
"Taking every chance they get to ruin your day with tits.
"Pretending their little ones need a comfort or a feed.
"Taking every chance they get to ruin your day with tits."
The song was inspired after Juliet was told off for breastfeeding her youngest child in a café. Juliet, whose children are aged between 15 months and 15 years, was breastfeeding her youngest child when another café customer made a snide remark under his breath.
She said: "I was just breastfeeding in a café and he was a young man who obviously thought I was ruining his day by feeding my child.
"To be honest I'm paraphrasing him but it was along the lines that I should have a bit more respect.
"I was quite floored at a time. I'm not quite sure how respect comes into it."
Rather than respond directly to man, she used sarcasm to write a song and she thinks that's what helped the video go viral.
She said: "[The breastfeeding in public debate] has always been tackled from someone getting criticised and then it comes up in the media but we took the issue on head on.
"Because we used humour, instead of a responsive reaction, I think it's been empowering for people and I think that's why people have got behind it.
"I guess what we were trying to do was put the attention on the bystanders rather than the feeders."
But Juliet never anticipated that the folksy pop song she penned and uploaded online to make fun of the anti-public breastfeeding lobby would strike such a chord with mothers around the world.
Juliet said she and Catherine – who call themselves Sparrow Folk and hail from Canberra - had been blown away by the response around the world and the song had been translated into 10 different languages.
Juliet said: "Hopefully people will lighten up about the issue and take the pressure off breastfeeding mums."
While the response to Ruin Your Day has been mostly positive, they have received some nasty comments online.
But Juliet responded: "We're certainly aware that our view isn't the view of everyone. For us that just shows there's even more reason to put it out there."
More on Parentdish: New poster campaign shows mums breastfeeding in public toilets