Nonce variation of the word bump, usually indicating the sound of someone or something tumbling down an uneven surface, or traveling on a rough road.
1833, Horace Smith, Gale Middleton: A Story of the Present Day, p. 229:"There he goes!" cried his delighted master, throwing down the poker and snapping his fingers in an ecstasy — "Bumpity bump! bumpity bump! Hope he won't stop at the landing-place — no — off again! All stone steps!
1998, R. Kiernan, Silk, chapter 1Daria closed her eyes, exhaling slow smoke through her nostrils, listening to the bumpity sound of wheels on the polished cobblestone unevenness of the street.
2002, Marian Keyes, Under the Duvet, p. 193:The rhythmic bumpity, bumpity, bumpity bump of a pissed academic with arthritic knees falling down the stairs, ricocheting between wall and banister as he went.
2011, Amy Seidl, Finding Higher Ground: Adaptation in the Age of Warming:Bang, bang, bumpity bump, I hear as spruce cones fall on the metal roofing of my woodshed.
