The point of the word "Duh" is to let the person you are speaking to know that they have just said something (a) obvious, (b) unintelligent, (c) unnecessary, or (d) all of the above.
And yet... it just makes you sound unintelligent.
INFJ - "Protector". Strong drive. Exceptional intuition. Private, only opening up to a few close friends. Always striving to understand the inner world. Good listener. Complex personality. 1.5% of total population.