[@Typhon]You mean something like [url=http://starwars.wikia.com/wiki/Shatterpoint]the Shatterpoint technique[/url] from Star wars?  That could work.  They'd have to sedate you after you got your powers, though, so you didn't break free before being sold off.
Not sure what the second worst one would be.  I'm thinking hypothermia, with only movement keeping you warm.