Yesterday my DS 10, said that he heard from a friend that when you say 69 people laugh so shouted it out in school playground loudly when I collected him after school and again at bus stop- he has no idea what it is or why it's funny. Told him to stop it and wasn't appropriate but unsure what to tell him as to why not to shout it as don't want him googling it and asking grandparents and teachers etc - any thoughts.