Suppose that there is a wormhole of the size of a ball. What will happen when your hand passes through it? Will your hand have a hole in its palm? If yes, then what will happen to the rest of the hand outside the wormhole?
http://www.quora.com/What-happens-if-you-push-your-hand-through-a-wormhole-whose-size-is-smaller-than-or-equal-to-your-palm