Unrehearsed readings are our most informal sort of theatre. Held about four times a year, they are generally hosted in someone's front room.
To put on one of these evenings, we simply source a complete playset with enough copies of the play for each actor to have their own and then invite a cast to just read the show aloud. There are no rehearsals, although generally those who are reading like to have read the play before they start.
Typically there will be a very small audience listening (sometimes less audience than those reading). It can be a great way to learn a new play, or a just a fun way to spend an evening either reading or listening. These are supposed to be members-only events, but the family of whoever is hosting the evening tend to get to listen in as well (we are generally blocking the telly).