|There's a reason they call money "dough".|
When someone says “I’d bet dollars to doughnuts Ed gets caught with a prostitute again.” It means that they’re fairly certain whatever they’re betting on will happen. The idea here is that you are so confident you would wager “dollars”, a valuable commodity, up against a person’s “doughnuts” a less valuable commodity.
The problem is it’s the 21st century now. America has a severe obesity problem. Everyone loves doughnuts. Doughnuts are no longer worthless items. “Dollars to dirt” might make more sense these days, but if you’re betting 20 dollars up against 20 doughnuts, the person putting up the doughnuts is taking the bigger risk. This saying is outdated and it makes little sense to anyone anymore.