Stupid

The teacher was trying to teach a psychology course. She told the class she wanted to conduct an experiment.

"Anybody in this class who thinks they are stupid, please stand." She said. A few moments went by and nobody stood. Finally, Mary stood up.

"So you think you're stupid, Mary?" said the teacher,

"No, Miss" Mary replied, "I think I'm pretty smart. I just hate to see you standing there all by yourself."