bet one's boots

Meanings:

• 1.

  American EnglishBritish Englishinformalcolloquial
  • To be extremely certain or confident about the truth of something; to be willing to stake a personal possession on its accuracy.

• 2.

  American EnglishBritish Englishinformalcolloquialdated
  • To wager or bet something (originally an article of clothing) as a forceful or hyperbolic expression of conviction.