A psych major and a law student walk into a library.

A guy is  looking for a place to sit in a crowded university library.  He asks a girl:  "Do you mind if I sit beside you?"
 
The girl replies in a loud  voice:  "I DON'T WANT TO SPEND THE NIGHT WITH YOU!"
 
All of the students in the  library start staring at the guy.  He became very embarrassed and moved quietly to another table.
 
After a  couple of minutes, the girl walks quietly to the guy and says with a laugh:  "I  study psychology and I know what a man is thinking.  I guess  you felt embarrassed, right?"
 
The guy  then responds in a very loud voice:  "$500 FOR ONE NIGHT? . . . THAT'S WAY TOO MUCH!". 

All of the students in the library look at the girl in shock.  The guy then whispers to her:  "I  study law and I know how to screw  people.".