A man was looking for a place to sit in a crowded university library.
He asked a girl in a whisper: "Do you mind if I sit beside you?
The girl replied, in a loud voice "NO, I DON'T WANT TO SPEND THE NIGHT WITH YOU!"
All the people in the library started staring at the man, who moved to another table.
After a couple of minutes, the girl walked quietly to the man's table and whispered with a laugh: "I study psychology, and I know how to embarrass people."
The man responded in a loud voice: "$500 FOR ONE NIGHT? I`M NOT PAYING YOU THAT MUCH!"
All the people in the library looked at the girl in shock.
The man whispered to her: "I study law, and I know how to screw people".