Duh! vs. Doy!

[David Bergdahl]

When my daughter Erika (35) was in elementary school "doy!" was the way
someone said the teacher was pitching instruction at too elementary a level;
when my daughter Esther (17) got to the same school it had become "duh!" so
I doubt that the Simpsons were responsible, unless the woman who does the
voice of Bart (an Ohio Univ grad), brought the expression with her...
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"Raffiniert ist der Herr Gott, aber Boshaft ist er nicht"
--Albert Einstein