A guy is looking for a place to sit in a crowded library. He asked a girl: “Do you mind if I sit beside you? 

The girl replied with a loud voice: “I DON ‘T WANT TO SPEND THE NIGHT
WITH YOU!”

All the students in the library started staring at the guy; he was truly
 embarrassed and moved to another table.

After a couple of minutes, the girl walked quietly to the guy’s table and
said with a laugh…”I study psychology, and I know what a man is thinking. I guess you felt embarrassed, right? The guy then responded with a loud voice: “$500 FOR ONE NIGHT? That’s Absurd!”

All the people in the library looked at the girl in shock.
The guy whispered in her ear: “I study law, and I know how to screw people”.