If you watch House of Cards, you might remember this scene from season one. (Warning: it contains the C-bomb, so don’t watch it if you’ll be offended by that!)
The joke is based on an entirely false grammar rule: “Thou shalt not end a sentence with a preposition.” Prepositions, remember, are words that describe the position of one thing in relation to another: at, to, in, of, about, from, above, etc. So you’ll hear people trying to obey this “rule” by saying things like this:
To what are you referring?
(instead of What are you referring to?)
There is the person about whom I was speaking
(instead of There is the person I was speaking about)
From where did he get his temper?
(instead of Where did he get his temper from?)
But they needn’t bother, because every modern-day authority agrees there’s nothing wrong with ending a sentence with a preposition. The “rule” was dreamed up by John Dryden in a petty attempt to prove that he was a better poet than Ben Jonson. He invented some hogwash about how English should abide by the same preposition rules as Latin, which made no sense, since they’re different languages with, for the most part, very different rules.
So if anyone scolds you for saying “What are you looking at?” instead of “At what are you looking?”, you can shame them with your superior knowledge of both grammar and 17th-century poetry – or just send them the link to that YouTube clip above.