bet one's bottom dollar

Meanings:

• 1.

  USUKgeneralinformalcolloquial
  • Be completely certain of something; regard an outcome as almost guaranteed.
  • Express a strong conviction about a future event by saying one would stake even one's last money on it.

• 2.

  USUKgeneralinformalfigurative
  • Vouch for or risk one's last resources (money, reputation) on the truth or likelihood of something.