English professor

An English professor is standing in front of his class giving a lecture on proper punctuation.

Professor: "I've noticed a lot of people using quotation marks for emphasis, and I just wanted to clear this up because it can cause a lot of confusion in certain circumstances."

He puts up a picture on the screen with the words "What is the sound of one hand clapping?" above a picture of a man in deep thought.

He then puts up a picture with the words "'What' is the sound of one hand clapping?" above a picture of a man waving his hand around with the hand saying "What what what what...."

The class has a sensible chuckle.

Professor: "The answer to the question, by the way, is this." And proceeds to clap with one hand, rapping his fingers against his palm.

A student in the class, thinking to take the haughty professor down a notch, says, "Okay then, if a tree falls in the woods and no one's around to hear it does it make a sound?"

Professor: "No."

Student: "What?"

Professor: "Please, hold your applause."