Australian here. I grew up in Sydney and heard this phrase for the first time only a decade ago, in my 40s, yet it rings so true to me. Someone with a snobby attitude, who privately skimps on the essentials so as to make a flashy display -- that is what the phrase says to me.
Some real-life examples:
Sends kids to school in shabby, outgrown uniforms, with shoe soles tied up with rubber bands and no sanpro for menstruating DD. Refuses to organise HS for DD. Challenged by teachers, responds by taking kids on six-week trip to California, including Disneyland, in school term.
Sends DS to elite selective school in dirty uniform with only one shirt, one set of briefs and one pair of socks for the week. Approached by neighbour, whose son attends same school, and offered free hand-me-downs. Physically assaults DS and throws him down the back steps for "shaming" them.
DD wins scholarship to decent private school. Refuses to buy DD uniform or school books because saving up for next flashy foreign trip. DD put on detention by school, with scholarship at risk. DD falls behind in maths and is put in remedial class.
DD wins second scholarship for Years 11 and 12. Refuses DD school books and uniform, says that in Charles Dickens's day children were sent out to work at 12.
Many years later, DS becomes live in carer. Refuses to let DS make essential repairs to the house, even simple things such as having the carpets steam cleaned for the first time in 40 years. DS so distraught he takes ADs. DD comes to help, has to wait until midnight to clean filthy house without interference.
Yes, I have had a gutful of AFCNK. It is a stressful and shitful way to exist. I raise my DC very differently, and with plentiful socks and knickers. Boring, as my DPs would say. But a solid foundation for life's adventures, which are best undertaken in adulthood.
Extended family members still mention my childhood travels. I politely refuse to discuss them. "But I'd love to tell you about my first backpacking trip in South America, saved up and paid for when I was 26." Oh, and I took heaps of knickers on that trip, and a good polarfleece, but no fur coat!