Answer:
His bet, in addition to supporting the wife, is something he cannot predict.
Step-by-step explanation:
Smiley bets against the health of Parson Walker's wife, which is already incongruous, because it makes him cheer against a person, wishing that he does not win the disease, that is, wishing that he die. In addition, he bets on something completely random that he has no control over, besides being completely irrelevant to him, since he won nothing by losing or winning the bet.