Boom-pah rhymes with "oompah," an onomatopoeic word based on the sound of a tuba. "Oompah" dates back to the late 1870s.
They blew on bazookas and blasted great toots
On clarinets, oom-pahs and boom-pahs and flutes!
Great gusts of loud racket rang high through the air.
They rattled and shook the whole sky!