Reported in Notes and Queries in 1870:
The taking of the United States’ census, now nearly completed, has brought to light some curious specimens of given names. […] In Smythe County, Virginia, a Mr. Elmadoras Sprinkle has called his two sons Myrtle Ellmore and Onyx Curwen, and his six daughters Memphis Tappan, Empress Vandalia, Tatnia Zain, Okeno Molette, Og Wilt, and Wintosse Emmah. The great number of persons surnamed Sprinkle in that county is given as the excuse for these extraordinary names.
I’m not sure how true that last sentence is, but Elmedorus Sprinkle did exist, and some of his kids did have unusual names. Here’s his family on that 1870 census:

According to Find a Grave, Elmadorus Sprinkle married three times, and had children with his first and third wives.
With his first wife he had about 6 children, but we only know 4 of the names: Matilda Jane, John William, Memphis Tremain and Latincy Jane.
With his third wife he had 5 more children named Myrtle Elmore, Okinna (or Okeno) Maletta, Og Wilt (or Ogwilt, or Willie), Emma Wintossee, and Onyx Curwen.
Source: “Curious Christian Names.” Notes and Queries 10 Dec. 1870: 499.
If my name was Ogwilt and my little sister was Emma…That would never be OK :-/
No, definitely not.
I wonder how they came up with “Ogwilt”…?
Onyx is actually in my top 10 names for boys right now, love it.
Dr. Onyx Curwen Sprinkle (1867-1954) was my grandfather. His middle name was for Dr. John Curwen of PA, who was his mother‘s guardian when she emigrated from Letterkenny in 1849.
Thank you for that explanation, Robert!