I don't know with other people, but my family usually will use hints when we need to talk about something serious in front of the kids without they knowing that.
For example, when we buy an ice cream and we don't want those kids to know (because if they eat ice cream, they might get cough and cold), so sometimes we spell it like, "Kakak, Ibu beli I-C-E-C-R-E-A-M. Nanti la kita M-A-K-A-N, bila budak budak ni T-I-D-U-R".
Haa, got it?
Or sometimes we speak in English, cause some kids don't really understand.
So one day, when I talked to my aunty in a car, and we don't want the kids to know it, we speak in English.
And suddenly we heard Damia who sat at the back of the car said, "Oh My English!"