Erm. awkward.
WWYD if zombies were real? o:
Buy out my local supermarket, employ the zombies as staff, and see if anyone noticed the difference.
WWYD if you were told the only way someone was going to live was through a bone marrow transplant from you, but it was someone you hated?
It would depend on the person and how much I hated them. Just a regular joe like me that I hate, sure I'd go through with it. If it were a known world-wide criminal, like Bin Laden for example, oh heck no.
WWYD If God Him/Her self (depending on which religion you follow) walked up to you and told you to change your ways or the world will end in a week.