OK... heres a start... Encyclo Britan

IRONY, a form of speach in which the real meaning is concealed or contradicted by the words used. It is particularly employed for the purpose of mockery and contempt. The Greek word was used for an understatement in the nature of dissimulation. It is especially exemplified in the assumed ignorance which Socrates adopted as a method of dialectic, the "Socratic Irony". In tragedy, what is called "Tragic Irony" is a device of making a character use words which mean one thing to him and another to those aquainted with the real issue.

My question... is it appropriate to use "Tragic Irony" off stage? ttr