While not precisely 'Dead Letters', our English stands test of time, but I miss it being colorfully used.

Myself, Shakespeare was fun (not easy, but...) to read because so many if not endless creative phrases.
The very best modern example, that hordes agree with, comes with "Oh Brother Where Art Thou". I can't watch or read it without laughing repeatedly, despite countless runs, but not as normal comedy; it is brilliant.
The script celebrates those writer's (Coen Brothers) inner Bard throughout, one scene closely with Et Tu question....

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Everett is stunned.

EVERETT
So you're against me now, too!... Is
that how it is, boys?

Silence. No one wants to meet Everett's eye. He is saddened.

EVERETT
The whole world and God Almighty...
and now you. Well, maybe I deserve
this. Boys, I... I know I've made
some tactical mistakes. But if you'll
just stick with me; I need your help.
And I've got a plan. Believe me,
boys, we can fix this thing! I can
get my wife back! We can get outta
here!
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For those wishing more, actual script here at https://www.dailyscript.com/scripts/o_brother.html Even the descriptive setups for scenes, just so dang good.