IT'S ALL ABOUT POSITION

Teacher:  Class, what's wrong with this sentence:  I think you're great; so where do you want to do it at?
Student:  You ended the sentence with a preposition.
Teacher:  What should you say?
Student:  I think you're great; so where do you want to do it, your place or mine?
Another student:  You're still ending the sentence in a proposition!