Not all strictly metaphors, but worth a raised eyebrow (or two):

Jesus to the crowd in the Sermon on the Mount:

“How can you possibly tell your brother, “I think a see a little speck in your eye,” when you have a log sticking out of your own eye?”

– Matthew 7:3

Jesus to the Pharisees who kept the man-made rules of the Mishnah but not God’s commandments in the Torah:

“You blind guides! You strain the gnats out of your soup [the gnat is an insect that is not kosher and should not be eaten], and then you swallow a whole camel!”

– Matthew 23:24

This, however, is quite a good one and does makes sense:

“If you meddle in a quarrel between two other people, you will end up like somebody who has picked up a mad dog by the ears.”

– Proverbs 26:17

I like many of these little ones:

http://www.geocities.com/bible_translation/otidioms.htm

Especially: “Their throat is an open grave = they speak deceitfully”

There was one Kirk Cameron (the actor from Growing Pains who turned fundy) did on a banana’s existence being proof that there’s a God. He used the grooves in the banana and put them up to his own hand, showing that they fit perfectly and that only God could have done this. The only problems with this are 1.) Wild bananas are cultivated specifically to become this way, and have evolved, and 2.) It was pretty ironic that he was waving a banana in everyone’s face while adamantly denying the fact that he is a primate. I put a link below… he calls it “the atheist’s nightmare.” How does he explain a pineapple?