Possible Clues:

• When Juliet asks "wherefore art thou Romeo?"
• Last part of 'Waiting for Godot'
• When Hamlet says, "The play's the thing ... "
• Second half of a musical
• The end of ''Evita''
• When Katherine and Petruchio meet
• It's when Macbeth kills Duncan
• When Polonius says 'Brevity is the soul of wit'
• When Rosencrantz and Guildenstern make their first appearance
• Second part of plays