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general::
Phrase(s): How dumb do you think I am?
Inf. Your question is insulting. I am not stupid. (Shows agitation. An answer is not expected or desired.) • Mary: Are you really going to sell your new car? Sally: Come on! How dumb do you think I am? • Tom: Do you think you could sneak into that theater without paying? Bob: Good grief! How dumb do you think I am?
McGrawhill's American Idioms And Phrasal Verbs