This should be taught in schools or at the very least dentists surgeries. The amount of teeth i chipped as a kid.
Also on a similar note if you put a wine bottle in base first into the heel of your shoe and repeatedly hit against a tree the cork will come out the top (marginally more romantic on a picnic) (best avoided for bubles though :rofl:
Also if the cork's pushed in you can retrieve it with a shopping bag pushed through the neck which envelopes the cork and pulls out round the sides.