Here's the catalog entry for the sheet music at Indiana State University Library. It contains more lyrics than I've found anywhere else:

Title: When Yuba plays the Rumba on the Tuba.
First Line: His name was Yuba! He was homely, he was dumb; and so was Yuba just a big ambitious bum
Chorus: Down in Havana there's a funny lookin' boob-a; he plays the Rumba on the tuba, down in Cuba.
Music by: Hupfeld, Herman.
Words by:
P/P/D: New York : Harms Inc, c1931.
Location: SPC, KIRK PS 1930-1939