Little Johnny's at it again......

A new teacher was trying to make use of her psychology courses. She started her class by saying, 'Everyone who thinks they're stupid, stand up!'
After a few seconds, Little Johnny stood up.
The teacher said, 'Do you think you're stupid, Little Johnny?'
After a few seconds, Little Johnny stood up.
The teacher said, 'Do you think you're stupid, Little Johnny?'
Spoiler: