Possible Clues:

• When Hamlet kills Polonius
• When Caesar asks, "Et tu, Brute?"
• Middle part of a Shakespearean play
• When Nora leaves Torvald in 'A Doll's House'
• End of 'Lohengrin'
• When Hamlet says "To be, or not to be"
• When Hamlet says ''To be or not to be''
• When Caesar asks "Et tu, Brute?"
• 'August: Osage County' finale
• When Romeo kills Tybalt, in 'Romeo and Juliet'