Is it OK to shush people during a movie at the cinema?

It’s no secret a chatty person (who can’t whisper if their life depended on it) and a cinema aren’t a good mix. And now we have mobile phones dinging, lighting up the surrounds and even people taking calls on them during a film.

While it’s annoying if you hear other people chatting away, if you shush them, there’s a chance they’ll shush you back or worse. So, other than a Jaffa to the back of their head, what can you do?  

Have you ever had a movie spoiled by a talkative fellow movie-goer? What did you do?

Is it OK to shush people during a movie in the cinema?