Green’s Dictionary of Slang

wink out v.

(US) to die.

[US]M. Thompson Hoosier Mosaics 17: Berry Young took it awful hard ’bout the gal, an’ he’s been sort o’ sinkin’ away ever sence, an’ now he’s jist ready to wink out.
[US]Ade Hand-made Fables 274: His Pals came to see him just before he winked out.
[UK]P. Hoskins No Hiding Place! 192/2: Winked out. Died.