Pandora's box: once opened, troubles pour out. In the myth, only hope stayed inside.
Pandora, the first woman in Greek myth, was given a jar (later called a box) and told not to open it. She did, and every evil flew out into the world. Only hope stayed inside.
Bringing up politics at Thanksgiving in Waco. Pandora's box.
Changing the billing model mid-quarter could open a Pandora's box. Map the risks first.
Practice it in Skepsis