In drama, Catharsis refers to a sudden emotional breakdown or climax in the audience that constitutes overwhelming feelings of great pity, sorrow, laughter, or any extreme change in emotion that results in the renewal, restoration and revitalization for living.

"Cathartic roleplaying" is a term used notably in Australian larp and other systemless games. This is often associated with horror games, referring to serious games which bring out extreme changes in emotion for the players -- either during the event or afterwards upon reflection. The convention glossary suggests various colloquial usage such as 'Cathart me gently with a chainsaw', and 'Who catharted?'.

References:

• An Australian Convention Roleplaying Glossary
• Cathartic Role-Playing Workshop Zero in Brisbane, Australia (Oct 1993)