18 Feb 11, 05:38PM
I'll put the answer for anyone who is curious.
[SELECT ALL] Code:
Answer:
Pull one ball out and immediately swallow it. The judge will only be able to determine which ball you pulled by looking at which ball is still in the bag. Because both balls were black, the ball left in the bag is black, therefore the judge must assume you swallowed the white ball or risk exposing his actions.