Bet One's Boots Meaning

(idiomatic) To be absolutely sure of something; to be certain enough to wager an essential possession.

Example: 1913, D. H. Lawrence, Sons and Lovers, ch. 12:
  "You see," he said, "she never knew the fearful importance of marriage . . . and treated him badly, I'll bet my boots."
1915, William Somerset Maugham, Of Human Bondage, ch. 27:
  "If a man tells you he's a gentleman you can bet your boots he isn't," he retorted.
2011 April 24, D. D. Guttenplan, "Scotland Wrestles With Question of Tuition Fees," New York Times (retrieved 19 Jan 2013):
  Lord Sutherland sees tuition fees in Scotland as inevitable. “Only you can bet your boots they won't call it a fee,” he said.