Last summer, a teenager I know – let’s call her Sarah – threw a pizza party at her parents’ summer house. She invited a dozen friends. So far, so normal. But just before the party started, a friend-of-a-friend of Sarah’s decided to post details of the gathering on social media.
Within the hour, as Sarah’s parents were ordering the pizzas, their beach house was overrun by hundreds of teenagers, most of them complete strangers. Cue panic from the host, horror from her parents and, eventually, a visit from the local police, who shut the party down.