So you post a quote from a movie, book, tv show, or song (or even trailers!). Anything that isn't generic. And the rest guess who said it and where it's from.
Oh, and DON'T use google search. (That would be a cheat!) XD
PS: sorry for late edit.
2nd EDIT: Guessers may ask for hints, but the quote-poster is limited to answering yes or no. :P