Nothing.
In absolute English, ending a sentence with a preposition is technically incorrect as it is impossible based on a classical understanding of language, whereby that sort of thing genuinely is impossible. For example, in Latin you literally cannot end a sentence with a preposition, based on the meaning of the word itself. This is controversial when applied to English the spoken language, since as you rightfully point out, many colloquial phrases end in prepositional words.
Hence my CT, which is mocking Grammar Nazis who are willing to create ridiculous sentences (like the one in my custom title) purely to stick by the rule, even when nobody would actually say that. The title itself is a quote from Winston Churchill, who used it to put down somebody who rebuked him for ending a sentence with a preposition.
So yeah.