In folklore: good luck.
In reality: a black eye, frequently.
the tapered part of a champagne cork before it is inserted into a bottle is like a wine cork cylindrical and uniform
Never use a corkscrew on a champagne bottle.
slice off the top of the cork and use a corkscrew to pull out the remainder, however if the cork is crumbling, push the remainder into the bottle and use a strainer to catch the bits. Not elegant but who knows when it is in the glass
The wire collar that holds the champagne cork in place, is known as a 'muselet'.
Then air was leaking into the bottle and it's probably bad.
Carbon dioxide is produced from yeast. This carbon dioxide causes champagne to bubble and the cork to pop.
Champagne corks are shaped like that due to the extreme pressure in a champagne bottle...the shape helps ensure that the cork will not fly out under the carbonation.
Away from your face and supposedly into the faces of others.
The wire cage is to help hold the cork in place against the high pressure inside the bottle.
When opened, a bottle of sparkling wine makes a popping sound as the cork is forced out of the neck by high pressure escaping the bottle.