This is a bit nuts!

Colin Farrell's new crime thriller "Dead Man Down" opens this Friday.  And to promote it, an ad agency in New York pranked a bunch of people by staging a fake murder in an elevator, and letting them walk in on it.

When the elevator doors opened, they saw a guy strangling another guy with a rope, and a lot of them just screamed and ran away.  But a surprising number actually tried to stop it. Oh and one idiot just stood there taking pictures with his cell phone!

What would you do?!

Here's the trailer!