Green’s Dictionary of Slang

(US) an oversized shoe.

1917		T.A. Dorgan in Zwilling TAD Lex. (1993) 86: (IS: Dancing with a guy who wears a no 11 shoe [who] thinks himself the champion of the world) If those violin cases came down on my feet I’d declare war.
1925		T.A. Dorgan in Zwilling TAD Lex. (1993) 86: Did you get the pair of dogs on the twist and twirl who is to play Cinderella? If they’re not violin cases I’m a riff.
1935		A.J. Pollock Und. Speaks.
1946		Mezzrow & Wolfe Really the Blues 33: You stood up and put your weight on these violin cases.