I found this question from Ian Hacking's book on probability and induction.
Diogenes is a cynic. He thinks the Maple Leafs will come in last in their league next year. His betting rate that they will come in last (proposition B) is 0.9. His betting rate that they not come in last (proposition ~B) is 0.2. Make a sure-loss contract against Diogenes.
It seems that a sure-loss contract is one wherein Diogenes loses every time. I don't understand how to make one from the given information though. Are you supposed to simply state prices that would provide Diogenes with a net loss every time?