At the start of 2025, a chat appeared on the encrypted messaging app Telegram. It was named Are We Dating The Same Girl? At first only a few hundred people joined. Soon that was thousands, and its content went from details of young women’s dating history, to revenge porn - sexually explicit videos and images. BBC Trending traces the Telegram group’s origins back to Are We Dating the Same Guy? groups on Facebook. But how did they first come about? Why are they seen as an important safety tool for some and something that has ruined lives for others? And how did the idea spread to Telegram, with serious consequences?