The etymology of this word has always fascinated me.

rube (rube): / roob /
noun

(1) an unsophisticated awkward person, especially from a rural area; someone who is rustic; hick
(2) an inexperienced or naïve person

[From English ‘Rube,’ a nickname associated with the forename Reuben.  Its use in this sense probably stems from Reuben being considered a common name among country dwellers.]

Usage: [from Dreamdarkers] I smiled briefly as I realized the old rube possessed a reservoir of character with which I was unacquainted.