be an insult to somebody’s intelligence
From Longman Dictionary of Contemporary Englishbe an insult to somebody’s intelligencebe an insult to somebody’s intelligenceSTUPID/NOT INTELLIGENTto offend someone by being too simple or stupid Some advertising is an insult to our intelligence. → insultExamples from the Corpusbe an insult to somebody’s intelligence• It is an insult to our intelligence.