Well, there is the famous party scene in Act II of Wilde's _Lady Windermere's Fan_
What about Act II of _A Woman of No Importance_ also by Wilde? It has lots of famous witty remarks.
Wilde's other plays are _An Ideal Husband_ (also witty) and _Salomé_--an exercise in decadence.
If you want other Irish playwrights, John Millington Synge is very well known. Try the opening to _The Playboy of the Western World._
William Butler Yeats (1865-1939) wrote many famous plays. _On Baile's Strand_ is one.
Samuel Beckett (1906-1989) was Irish but wriote in French,. Do the ending or beginning of his _Waiting for Godot._ It's absurdist theater and very strange. He also wrote some very short meorable plays: "Act Without Words I" and "Act Without Words II," plus "Not I," and "Breath." "Breath" has no cast--again, an experiment.
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