My math teacher called me average.

This joke is a stellar example of a pun, a form of wordplay that delights in words having multiple meanings or sounding like other words. The humor here springs from the double meaning of "mean." When someone is called "average" in casual conversation, it often carries a negative connotation, suggesting they are unexceptional or mediocre. Naturally, one might feel insulted, and exclaiming "How mean!" perfectly captures that feeling of being unfairly judged or treated.

However, the punchline cleverly pivots to the mathematical definition of "mean." In the world of numbers, the "mean" is a specific type of average, calculated by summing all the values in a dataset and dividing by the count of those values. So, while the student perceives the teacher's comment as an emotional slight, the teacher might have simply been making a factual, statistical observation about the student's performance relative to the class, making the student's reaction a brilliant linguistic twist.

It's a clever little jab at the sometimes-dry world of statistics, reminding us that even precise mathematical terms can be the source of a good laugh. This joke highlights how language can be delightfully tricky, especially when we navigate between emotional responses and exact definitions, making for a perfectly "average" (in the best sense of the word!) schoolyard chuckle.