By the skin of your teeth

If you pass a test by just a few points or win a contest by a tiny bit, people might say you did so 'by the skin of your teeth.' In other words, you just barely did it. The only problem with this expression is that your teeth don't have skin! But sometimes they have a film on them, especially first thing in the morning. If you feel that sticky film, it's time to brush your teeth!

Other links:

Have Your Heart in Your Mouth

Butterflies in the Stomach

Nigerian Proverbs

Thai proverbs

Earth