Green’s Dictionary of Slang

German flutes n.

a pair of boots.

1857		‘Ducange Anglicus’ Vulgar Tongue.
1858		A. Mayhew Paved with Gold 169: ‘I’ll have yer down on “the last card of your pack” as soon as I’ve laced my “German flutes”’ — meaning thereby that when his boots were arranged he would throw Philip on his back.
1864, 1867, 1870		Hotten Sl. Dict.
1927		Shields Dly News 2 Dec. 2/7: I put on my ‘German flutes’ (boots) and my ‘bucket afloat’ (coat).
1935		A.J. Pollock Und. Speaks.
1942		D. Runyon in Star (Marion, OH) 31 July 6/8: The old glossary gives both ‘daisy recroots’ and ‘German flutes’ for boots.
1960		J. Franklyn Dict. of Rhy. Sl.