Little Johnny farts in the classroom and his teacher gets really upset and throws him out.
The principal walks by and sees him.
He asks, “Little Johnny, why are you sitting outside your class laughing?”
“I farted in class and the teacher threw me out.”
The principal asks him again, “Well then, why are you laughing?”
“Because those idiots are sitting in the class smelling my fart while I’m outside in the fresh air.”