In Trail of Cthulhu, if you suffer madness you must leave the room while the other players and DM debate the most appropriate manner in which to gaslight you. They may, for example, pass notes to each other and exchange meaningful glances. Or, they could all agree that some important recent event didnt happen and will react with confusion when you bring it up. Or they could come up with any number of other thjngs.

Random Trivia: I gotta start doing this in all my comments