Off the top of my head...
Two strangers, a man and a beautiful woman, are seated next to each other on a cross country flight. Once the flight takes off they make small talk and they find out they are both flying to the same destination for different types of business.
After a little while the man offers a shocking proposal to the woman -- he offers her a million dollars if she will spend the night with him. At first the woman is indignant and appalled at the offer, but after a half hour or so she mulls things over in her head and decides that the offer is just too much to pass up, so she accepts.
As the flight nears the destination, the man turns to the woman and tells her that he's very sorry, but he actually doesn't have a million dollars. He then asks her if she'll reconsider the offer, but for only a hundred dollars.
Now the woman is truly appalled. "What do you think I am?!" she asks the man incredulously.
The man replies "we've already established that fact. Now we're just quibbling over the price."