if they say that they are probably dead

When you eat dirt for the first time and leave your family to build a shack in the woods

If you hear someone say: I am dead, he / she probably means that he / she did something bad and will get in trouble

For example:

You are playing football in the backyard with a friend. You shoot the ball straight to a window and you break the glass.

You say to your friend: shit! I'm dead!

Cause you did something that other people won't be happy about