bodaccea is right, you can tell people to do anything.
a docu i watched showed a faked quiz show (based on that famous experiment), where contestants were to zap a man inside a box. they couldnt see him, and they were unaware there was no real electrocution.
both the contestants and the audience believed the man would get zapped w increasing ammounts of electricity for each incorrect answer
the contestants continued to zap the man, "knowing" the woltages were becoming dangerously high, simply cus the host insisted "go ahead"
some tried to politely, laughingly, complain, but still zapped the man, simply by being told again to do so.
a tv host and tv cameras outweighed the mans health. on "applause" the audience would keep applauding
eventually the man screams, begs for the tv-show to end, screams stuff like "let me out! its not funny anymore" etc, and at this point only a tiny minority of contestants refuse to shock him any further.
most of them continue even after he goes silent, "playing dead", demonstrating that people are capable of murder... simply because a tv host goes "ignore it. go ahead."
afterwards, contestants met the actor, and reassured it was all an experiment, many of them broke out in tears