Green’s Dictionary of Slang

daniel n.1

[? corruption of SE dangle]

(US black) the buttocks.

[US]Furry Lewis ‘Good Looking Girl Blues’ 🎵 Lord my good girl says she don’t want me no more, / But she’s on my dabiel, lord, every where I go.
[US]Mezzrow & Wolfe Really the Blues 85: He’d pull the chair out from under some dignified dowager and catch her just before she went to fall on her daniel.