Some mums chuckled. I took photos and sent them to my friends.
As I left, I said it was good when they have other people tell them off.
"That's good because some people get a bit funny about it," she said.
Having not long earlier watched the footage of a child screaming down an aeroplane last week, I do wonder if this is one way we are going wrong "these days".
When I was a kid, families were close. Aunties and uncles and neighbours would tell each other's kids off if they stepped out of line.
We have lost that community - our "back-up". And, the "line" isn't the same as everyone else's any more.
When someone else tells my kids off, they are reinforcing the same things I have been saying. A lot.
Maybe through tiredness, inattention, or perhaps anger or frustration I am sometimes trying to contain, I am a bit inconsistent with things, or not hard enough in the first place – or maybe just because I am their mum – they still do things I have asked them not to, in spite of time-outs or the removal of favourite toys.
But when someone else steps in, by crikey do they listen.
When someone else tells them off, it's another source reinforcing that whatever they were doing isn't cool.
It teaches my kids that their mum isn't the only bad guy in the world and other people have rules and expectations, too.
When good friends come over and see my 5-year-old daughterat her worst, a couple of them raise their voice or say in a sort of mock shock, which she takes to be real: "You shouldn't speak to your mum like that!"
It gives me great joy to watch her pull her head in instantly. Mission accomplished.
There are some parents who don't like other people telling their kids off.
But, if my kid is being a brat, and my efforts to stop it are not working, please, PLEASE, back me up!
I don't care if another mum is precious about her kids. If I see mums battling, I always say something to the child like: "You have to listen to your mum, she looks after you."
You don't have to be mean about it. Often it's enough to hear a stranger's voice and it distracts the kid from protesting against mum.
Sometimes, that might be all someone needs.