blankety-blank
From Longman Dictionary of Contemporary Englishblankety-blankblank‧e‧ty-blank /ˌblæŋkəti ˈblæŋk/ adjective [only before noun] American English spoken SWEARused to show annoyance when you want to avoid swearing The blankety-blank key is stuck!Examples from the Corpusblankety-blank• That blankety-blank little idiot took my watch!Origin blankety-blank (1800-1900) blank; from the idea of an empty space taking the place of an impolite word