blank ‧ e ‧ ty-blank /ˌblæŋkəti ˈblæŋk, ˌblæŋkɪti ˈblæŋk/ BrE AmE adjective [only before noun] American English spoken
[ Date: 1800-1900 ; Origin: blank ; from the idea of an empty space taking the place of an impolite word ]
used to show annoyance when you want to avoid swearing:
The blankety-blank key is stuck!