I feel for you OP, had The Dark Knight ruined for me by some asshole who wouldn't shut the hell up and wouldn't turn his stupid phone off.
To this day I wish I'd told him to shut the fuck up - because chances are your not the only person being pissed off by their douchebag behaviour. Now I just avoid going for a few weeks if I can help it so that the screen is nearly empty.
Nouw said:
Yup, some people don't seem to freaking understand that the people in the film aren't real (well the actors are but...). THEY CAN'T HEAR YOU, YOU DON'T NEED TO REACT TO WHAT THEY DO.
The only group more annoying are the parents who assume that 12A (don't know what it would be called in America) means you can take your 4 year old to go watch Terminator 3 (actually happened).