bet dollars to donuts

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb idiomatic To suggest that something is very likely to be true or that one has a strong hunch about something. Related to the earlier 'bet dollars-to-buttons' and 'bet dollars-to-dumplings' that appeared in the 1880s, meaning 'almost certain' because the dollars are bet against something near worthless, and perhaps zero shaped.