A very shy guy goes into a pub on Valentine's Day and sees a beautiful woman sitting alone at the bar.
After an hour of gathering up his courage he finally goes over to her and asks tentatively, "Would you mind if I bought you a drink?"
She responds by yelling at the top of her lungs, "No, I won't sleep with you tonight!"
Everyone in the pub is now staring at them. Naturally, the guy is hopelessly and completely embarrassed and he slinks back to his table totally red faced.
After a few minutes, the woman walks over to him and apologises. She smiles at him and says, "I'm really sorry if I embarrassed you just then. You see, I'm a graduate student in psychology and I'm studying how people respond to embarrassing situations."
The man responds at the top of his lungs, "No I won't pay $200!"