DD13 planning group sleepover. She was planning what they would be doing with one of the other kids who will be there and I overheard the other kid (also 13) say they’d bring Cards Against Humanity. I’ve never played it but have heard it referred to on here by some posters as a bit full on. Am not sure whether to ‘accidentally” discover them playing if and stop it or just let them get on with it as a bit of harmless boundary pushing. As I haven’t actually seen/played it, I have only the impression of it I’ve got from Mumsnet so have no opinion of my own. What would you do?