In your class group chat, someone posts something mean about a kid who isn't in the chat. People start replying — jokes, laughing emojis, worse comments piling up fast. The chat lights up. Then your phone buzzes too: people are looking to see who's joining in. Staying silent is noticeable. Adding a laughing emoji would be the easiest thing in the world, and you'd disappear back into the crowd. The kid it's about can't see any of this. But every message is a permanent thing, sitting in writing, that they could find one day. And right now, the count of who piled on is being recorded forever.