The definition of blankety-blank is an expression used when a person doesn't want to actually say swear-words or curse words, but would like to express the sentiment.
(adjective)An example of blankety blank is what you would say when you pinch your finger in a drawer. You could say "this blankety-blank" drawer instead of using curse words to express your frustration.
See blankety-blank in Webster's New World College Dictionary
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adjective, adverb
Origin: see blank,