As Marty said to Clark, I'll say to you:
"You don't know when to quit, do ya Griswold?... Here's an idea: Why don't you give me half the money your were gonna to bet, then we'll go out back, I'll kick you in the nuts, and we'll call it a day!"
I won't even kick you in the nuts, if you don't want... I can even guarantee a 2% chance i can double your money if the moon is in Taurus and if the 3rd day of the second month lands on a thursday and is proceeded by a Mac Truck. Trust me, I have better odds than that f'n goblin.