The "canonical" rebuttal to this trope goes something like this:
"Who are you going with?" "Don't end sentences with prepositions." "OK. Who are you going with, bitch?"
However, from a grammatical standpoint, this doesn't actually work in the way it's intended. The "problem" (not actually a problem, as outlined by the main trope page) is that a preposition at the end of a sentence seemingly lacks an object. However, in the classic rebuttal, "bitch" is not functioning as the object of the preposition. It is functioning as an adverbial. Because it is an adverbial, it can appear in many places in the sentence. All of the following are legit ways to phrase the rebuttal:
"Bitch, who are you going with?" "Who, bitch, are you going with?" "Who are you going with, bitch?"
Two of which still end the sentence with a preposition, while still keeping the same meaning. In reality, the object of the "with" preposition is, in fact, "who." The sentence can be reworded (awkwardly) as "You are going with who(m)?" Or, "With whom are you going?"
One of the main problems with that sentence is that "Who" is not properly declined. "Whom are you going with?" is more correct than "Who are you going with?", though still not grammatically correct due to the nature of sentence structure in English.
"Grammatically correct" in this context means nothing: it's the speakers of a language (not language teachers or grammar books) who define what is correct grammar. English as commonly spoken allows split prepositional phrases as a result of fronting in Wh-movement ("What are you talking about?"), prepositional passives ("The problem was talked about", though this usage is uncommon) and relative clauses ("That's what I'm talking about!"). These types of fronting are common in many languages, and the fact that in certain other languages you can't strand prepositionsCase in point. In Spanish, for example, prepositional passives aren't allowed, and the other two types front the preposition as well as the question marker or relative pronoun. should be a sign that English treats prepositional phrases in a different way, not that English should be reformed to conform to those other languages. Also, in sentences like "I went in", the word in isn't even a preposition, it's an adverb.