$10 plane rides

In the outskirts of Chicago there is a carnival every year. One of the attractions is a small plane and for $10 you can go for a ride along with the pilot. Every year a man and his wife attend the carnival, and every year he asks his wife if they can go on the plane ride. She is very stubborn and responds with a quick "No." and the husband responds back "Why not?" which she responds, "Because 10 bucks is 10 bucks". So, year after year the husband attends the carnival and asks his wife if they can go for a plane ride. To no avail, her response stays the same, "Because 10 bucks is 10 bucks". The following year, the couple goes to the carnival again, and the husband asks about the plane ride once more. This time, the pilot overhears the conversation and decides to jump in. "I have heard you two argue about this plane ride for too long. I am willing to give you both a free ride on one condition." The husband is thrilled by this proposition and excitedly asks what it might be. "I'll take you both in the air for free, but you have to be silent. I don't want to hear one word out of your mouth. If hear anything I will charge you the $10 it costs to ride." Intrigued by the simple request the couple agree on the terms and head for the plane. The pilot and the couple get strapped in and he reminds them once more about their deal. The plane takes off and the husband is overjoyed. The skilled pilot begins doing barrel rolls loops and other aerobatic maneuvers. Even after all of his tricks he still hasn't heard a peep from the couple. Finally the pilot decides to land. He gets out of the plane and notices that only the husband is still in the plane. "Sir, where's your wife!?" he asks wildly confused. "Oh, she fell out after the third barrel roll." "Well, why didn't you say anything?!" "Because 10 bucks is 10 bucks."