The story
A variant of skinned (“having the skin removed; (informal) broke, penniless”, adjective). Any similarity to skin a flint (“to go to great lengths to gain or save something, particularly money”) (referring to the brittleness and hardness of flint which makes it almost impossible to remove just its outer layer without shattering it) and its derivative skinflint (“one who is excessively cautious or stingy with money”) is coincidental.
First known use, by meaning
- from early 20th c. Having insufficient or no money; broke, penniless.
Etymology from Wiktionary, CC BY-SA 4.0.