Mum and Dad went to a play in a restaurant as part of the Canterbury Festival; this was both a play taking place in the restaurant, and a play set in a restaurant (of an inn in 1950s Italy as it turned out). They were served a meal and occasionally found themselves part of the action.
While talking about this I made reference to "The Fourth Wall" a drama theory term that it turned out they weren't familiar with. In case anyone else is unfamiliar with it I'll briefly explain here.
Classically a stage has three walls, the one at the back, and the two wings (which allow actors on and off). The fourth wall is the one between the audience and the play. It is, of course, invisible, to allow the audience to watch the play, but exists to separate the audience from the world of the play.
Breaking the fourth wall (interacting with or acknowledging the audience) is now an almost overused technique in films, especially comedies. Charles Stross talks briefly about it, in reference to his use of the second person in his latest novel at the start of this film (him doing a reading; it's an hour long, but the bit I refer to is near the beginning).
 As this was a play in a restaurant rather than a restaurant in a play, the food was good, rather than cold, and/or fake.