The experiment:
The thought experiment was originally proposed as follows:
You wake up in the morning and find yourself back to back in bed with an unconscious violinist. A famous unconscious violinist. He has been found to have a fatal kidney ailment, and the Society of Music Lovers has canvassed all the available medical records and found that you alone have the right blood type to help. They have therefore kidnapped you, and last night the violinist’s circulatory system was plugged into yours, so that your kidneys can be used to extract poisons from his blood as well as your own. [If he is unplugged from you now, he will die; but] in nine months he will have recovered from his ailment, and can safely be unplugged from you.
The big questions are: Is it permissible, from a moral point of view, for a person to disconnect from the violinist even if it causes his death? Does the right to life include the right to use another person’s body? If not, disconnecting from the violinist does not violate his right to life, but merely deprives him of something (using someone else’s body). In Thomson’s words: “If you allow him to continue using your kidneys, that is a kindness on his part, not something he can claim from you as his due.” Likewise, abortion does not violate the fetus’s legitimate right to life, but only deprives the fetus of something (the non-consensual use of the pregnant woman’s body to which it has no right).
Consultant: Thomson, J. “A Defense of Abortion”. Philosophy and Public Affairs 1:1 (Autumn 1971): 47–66.

the art:
“Right to life”

The Famous Violinist is a “thought experiment,” not just an analogy to, say, pregnancy as a result of rape.

It is a way of testing our intuitions about what follows from ‘x has a right to life.’ If anyone has a right to life, the Famous Violinist certainly does.

Is it then morally wrong for you to unplug him?