So with Paranormal Activity 3 coming out in a few weeks I thought I would save them the trouble of writing the next one and do it myself. 

There is a family living in a house, some strange things start to happen.  Doors closing, lights turning off, sounds etc.  They start to get scared, and film all the time because its so crazy.  The camera is filming somebody doing nothing out of the ordinary and then one of the people goes flying as if an invisible force is pushing them.  The camera turns off so we have no idea what ever happened to them...the end. 

I have never seen any of these movies but this is how they all go.  Every preview is the exact same thing, just different people.  I can't believe people actually get paid for those movies. 

BONUS... here is the next Transformers (or any Michael Bay movie)

Explosions....Annoying guy likes hot girl.Establishing shot of just how hot said girl is. More explosions, hot girl runs in slow motion.  End of the world implications,and even more explosions. Robots say something clever and hip, hot girl runs in slow motion.........."Optimus!!!!" The end.