This question already has an answer here:
Recently in an episode of 'House of cards' they bring up the joke
"Two freshmen girls are moving into their dorm room together. One of them's from Georgia, one of them's from Connecticut. The girl from Connecticut's helping her mother put up curtains. Girl from Georgia turns to them and says, "Hi. Where y'all from?" Girl from Connecticut says, "We're from a place where we know not to end a sentence with a preposition." The girl from Georgia says, "Oh, beg my pardon. Where y'all from...cunt?"
Now, i suppose the punchline has something to do with the not-preposition, but what i don't get is why the Connecticut girl even considers that a sentence cannot end with a preposition? Is there any reason for stating that prepositions can't be on the end of a sentence? And if not, what is the punchline of this joke?
If this joke's punchline is not pertaining to English language or if this is not a grammatical joke, i'm sorry and will remove the question.