First and foremost, NO CHEATING! That means no google, no IMDb, etc. If you don’t know it, don’t post it.
Number two, don’t post any new taglines until the current one has been guessed correctly.
Third, no odd, off-the-wall, obscure movies that 4 people on the face of the earth have seen.
No movies before, say, 1965.
Foreign films are ok as long as the tagline is posted in English and the movie is at least somewhat known in the U.S. I realize that not all dopers are Americans but a good majority of us are.
Oh, and one tagline at a time, no hit and runs where you post 5 taglines out of turn and then everyone gets confused over who is trying to answer what.
Now I’ll start off with one of my favorites, an easy one: