plunkety-plunk
/ˌplʌŋkɪtɪˈplʌŋk/(also plunkitty-plunk, plunkity-plunk)
noun
A rhythmic plunking or twanging sound, especially as produced by picking a banjo or similar stringed instrument. Also as adjective: designating such a sound.
Origin
Late 19th century; earliest use found in ‘Mark Twain’ (1835–1910), author and lecturer (real name Samuel Langhorne Clemens). From plunk + -ety + plunk.