When Swedes want to talk about secret stuff in the presence of children, we invariably turn to English. This serves two purposes: 1. It works so well. 2. It speeds up the children's interest in learning English.
What language do you switch to? Have you tried Mandarin?
Repeat after me:
他们可以得到一些冰淇淋饭后
(mandarin speakers, feel free to correct my grammar).