be dollars to doughnuts that (something happens)
To be assured or certain to happen. The idea is that one is so confident in a particular outcome that they would bet money against something less valuable. It's dollars to donuts that Kevin will be late tonight—he's never on time.
dollars to doughnuts, it's
It's a virtual certainty, as in It's dollars to doughnuts that the team will make the playoffs. This metaphoric term pits dollars against doughnuts as in a bet. [Colloquial; late 1800s]