What would you do if you witnessed a murder in progress? Would you run away or would you help the victim out?
It's a moral dilemma that the vast majority of us will hopefully never have to face.
Although you would like to think that your instinct would be to help, it's just not that black and white. No one really knows how they react in such an extreme situation.
Which makes it the perfect scenario for a new experiential campaign. Yep, if you thought Nivea turning German air passengers into criminals was mean, you had better look away right now.
'Elevator Murder Experiment' - a new ad for upcoming movie Dead Man Down - makes Nivea's StressTest looks like a relaxing stroll in the park.
It features the reactions of members of the public when they open the doors of a New York elevator only to find one man trying to choke the life out of another.
Of course, it's not real; it's just two actors staging a life-or-death tussle to see how people respond. All the action is captured on hidden cameras inside and outside the elevator.
A lot of them scream and flee, one grabs a fire extinguisher and one man even tries to film the whole thing on his phone.
Created by Thinkmodo - the same evil geniuses behind another mean prank, Beauty Shop Scare - it's a stunt that is sure to have the internet talking.
Since its launch on March 4, it has attracted almost 500,000 views. We expect it will attract a lot more in the coming days.