There is no better time and place than when royals are in earshot to hear it. And doubly so when those royals wish you would be silent.
Username checks out?
And who decides what the right times and places are?
Any time and place other than a funeral or memorial service would be a good start. I can't believe there are adults here arguing that it's somehow ok to crash someone's funeral or memorial service to hurl insults at their relatives.
You take a guess, and if you guess wrongly, you get arrested.