Aged around 5, younger DS announced very loudly to the entire supermarket queue that he knew how babies were made. You could see all ears pricking up and he continued "first you have to commit sex" amidst the grins and giggles of everyone who heard (felt like the entire store).
One of our neighbours was a lovely black lady we are still friends with today, but one day when she came to visit, the TV was on and there was a black lady reading the news. Elder DS aged possibly around 3, looked from TV to neighbour and back again, looking slightly puzzled, then said pointing to each, "Two Josies!". Luckily Josie found it hilarious!