1) When you make a bet, lose - have the means to pay for the loss incurred, but change your mind the next day and offer something considerably less that what was initially agreed upon.
2) When you make a bet, lose and don't pay up.
(Me) - Yo Steve we had a $100 on that ball game last night.
(Steve) - I know but I thought about it today and I'm out, I'll give you $5 go buy a sandwich.
(Me) - Damn Steve you just "Roddy White'd" me!