Auntie is a moniker commonly used here to address women that are friends of your parents or your parents friends, or generally women older than oneself.
Here's the story:
My son,N and I were going to pick my duaghter, S from her music lesson, when this lady approached us. "Ai buay lew lian my? Chin pee" (Want to buy durians, very cheap.)
I politely declined as we had just had durians the day before from our regular supplier. While we were waiting for S's class to finish, N said: Mummy, can you buy durians? I want to eat. But I told him, that we could buy from our regular durian seller as the quality was guaranteed to be good.
After picking S, and when we were walking to the car, we noticed that the van selling the durians had moved to a spot very near to our car. N asked again: Can we try his durians? Please, mum, please?
I was about to say "ok, we will try some" when suddenly, the driver of the durian van came rushing towards me, saying: "Auntie, durians very cheap! Only $5! We got mountain cat, wild cat, sultan durians - all cheap cheap. Auntie, try la. Auntie, I promise you my durians very good one!"
What! A 50+ year old man calling me "auntie"!! I have many people complimenting me on my youthful looks and telling me I dont look a day over 35, and here was this old man calling me "auntie". Sorry, man, eh, uncle - you just lost my custom. I smiled and said "no, thank you", got into my car and drove away. I would rather buy from my regular supplier. He looks 40ish, and he calls me "sister".