"I am already dead"
Deriving from Omae wa mou shindeiru, it is usually used unironically among friends. It is also a cry for help that will be laughed at as you circle into the depths of despair, leaving behind any sanity you possess.
Joseph: Are you ready for the two hour school assembly?

You: "Watashi wa mou shindeiru!!!"
by Prof. Layton March 16, 2018
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