A dare that is done without hesitation no matter how harsh it might be, as long as there is at least 10 cents payment for the dare required.
Levi: "Hey man, I got an Aaron Dare for you... I will give you 20 cents if ya pull your dick out and shove it in that old ladys mouth! what ya say?"
(26 seconds later Donalds Dick is in Granny Margrate's mouth.)