Honestly, how many times do you have this conversation with your children? Or, the conversation which says: ''I don't care if it is 4am. Ring me and I will pick you up. Just ring me.''

I've moved from conversation two to conversation one because I am no longer any good to anyone at 4am. I haven't been awake at that time of day unless I am at an Anzac dawn service or in the middle of a hot flush.

When my kids lived at home, those discussions worked because I was on hand to observe and demand. These days, I have an idea that there is still some risky behaviour which is why I tend to ring my offspring at, oh, say 9am on a Sunday. Just to make sure they are alive.

And I've never had to do anything really dramatic when it came to rescuing my kids. If they drink or drug to excess, I have personally never observed it. Which may be because my children are at least smart enough not to want to be admonished to death.

Believe me, I'm capable.

So I was somewhat astonished to hear the story of a casual acquaintance. And to her I say: ''More power, sister.'' Her two daughters went to a party. The elder girl leaves a little early. A couple of hours later that girl gets a phone call from friends at the party telling her that her baby sister is unable to sit up, covered in vomit, and looked to be comatose. Maybe they used The Chair test. Maybe they just knew - and more of that later.

The older girl tells her mother that they need to drive back to the party to get the little sister. From here on in, it's a mother's tale.

The mother takes her to the emergency department of the nearest hospital. She is beside herself. But not too beside herself to video every single thing which happens to her daughter.

She videos the drip as it is inserted, the stomach pump, the abuse as the girl wakes up to what is happening around her. It's all on her phone.

Fortunately the child recovers. The mother keeps secret her video until the daughter tells her she plans to travel to Europe to party.

As I understand it, the mother offers to pay for the airfare so long as the daughter watches an unnamed video. Or there is some other negotiation. Anyhow, the girl watches the video. And, as local legend has it, never drinks to excess again.

Massive invasion of privacy? No question. Useful evidence in the battle to keep kids safe? At least one expert in the area says it can work - but you have to know your audience.

Paul Dillon, the director of Drug and Alcohol Research and Training Australia, says this strategy will only work if there is a lot of trust to begin with.

This is a bloke who has worked in this area for years - and he sees a lot of parents and kids getting the messages all mixed up.

The number one message to both parents and kids is that teaching young people how to protect themselves is the most important thing you can do. Which brings me back to The Chair.

A few years ago, I was at one of Dillon's presentations. This was right at the beginning of my experience of parenting Australian adolescents.

I volunteered to be one of those bunnies used to demonstrate up on the stage. I lay on my side to illustrate the recovery position, in front of a room full of disapproving parents. Never put a drunk person on her back. She will choke on her own vomit.

He's got an even better example now. He calls it The Chair. If your friend is so drunk that he can't sit on a chair and hold his head up, you need to call an ambulance, right now.

Dillon regularly receives emails from grateful teenagers who thank him for his practical tips. It's these hints which work.

Promoting abstinence doesn't work because Australian adults don't practise it. So the offspring of Australian adults - our children - don't understand why they should be abstinent either.

Dillon says the best thing we can do for our children is to teach them how to prevent harm - give information on short- and long-term harm as best as we possibly can.

He says two-thirds of Australian 12-year-olds have already tried alcohol.

I'd love to say they all think it tastes disgusting - but they don't. They keep drinking and so do their parents. By the time we become adults we learn our limits and we understand we can't write ourselves off and still function the next day. It takes younger people more time to understand that.

While they are learning, we need to make sure they, too, can take The Chair test.

■ Follow me on Twitter @jennaprice or email me