How do you react when someone says 'duh' to you in a rude way?

Like in a question earlier, someone asked who cheats more mean or women? And an anon girl rudely answers 'men, duh!'

Like that was supposed to be obvious or something.

Pissed me off. :-P

Anyways, how would you react?
How do you react when someone says 'duh' to you in a rude way?
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