Shibboleth

Shibboleth is a word game in which you must discover who your teammates are by giving subtle hints. You and your teammates have a shared word, as do your opponents, who have their own shared word. You can give freeform clues about your word, so that your teammates know who you are. Once you've learned who your team is, you can announce what your team is to win. Be careful, though—if the hints you give were too obvious, and your opponents discover your word, they can guess your word to steal your victory!