She yells at the top of her lungs, "No, I won't sleep with you tonight!"
Everyone in the bar is now staring at them.
Naturally, the guy is hopelessly and completely embarrassed and he slinks back to his table.
After a few minutes, the woman walks over to him and apologizes. She smiles at him and says, "I'm sorry if I embarrassed you. You see, I'm a graduate student in psychology and I'm studying how people respond to embarrassing situations."
At the top of his lungs, he responds, "What do you mean $200?"