Because the word “Savannah” sounds like “savanna” a female student incorrectly assumes that her professor is mocking her gender (those that descended from the savanna regions of Africa). Actually, he was simply stating that her parents, who reside in Savannah, Georgia raised her poorly.
The point of this comic, other than to introduce the world to another hilarious pun, is to let all women know that they should stop running their mouths off all of the time and think long-and-hard before attempting to form any opinions.