As I am now, I would stop before I 'killed' the other person, but that's probably because I already knew about the study. I don't know what I would be like if I had never become a sociologist.
The Milgram experiments, the Stanford Prison Experiments, the Tuskegee Syphilis Study, and Laud Humphrey's Tea Room Trade are all studies that I have used during discussions on ethics in tutorial classes that I TA'd while completing my Masters in Sociology. They illustrate very well the need for ethics in any research involving human beings, whether it be social science research, medical research, or any other kind - if it involves a human, then it should go through a rigorous ethics screening.
For those who are curious, the Tuskegee syphilis study involved deliberately denying medical treatment to black patients with syphilis in order to better understand the effects of syphilis on the human body. They essentially discovered that syphilis is Bad For You, at a cost of great human suffering. It was a gross human rights violation, and violated the Hippocratic oath.
In the Tea Room Trade, Laud Humphreys volunteered to be the lookout at park washrooms where gay orgies were going on. While he was on the lookout for the cops, he took down the license plates of the men who came to participate. Later, he contacted a friend in the Department of Transportation who provided him with the names and addresses of the people who the vehicles were registered to. He went, in person, to these people's houses to confront them on their actions. He discovered (much to his amazement), that many were married and identifying as straight. The Tea Room Trade is an excellent illustration of how informed consent, the rights of participants, and privacy requirements are all necessary for ethical research.