This does not work, and if anything, has been shown to actually accelerate the flattening of the champagne. This myth was tested by the "Mythbusters" on the Discovery channel during their "Viewers Choice Christmas Special", which originally aired on December 22, 2004. This is a great show to watch if you are interested in urban myths.

I don't know about a spoon - a cork would be better.

Champaign is a carbonated beverage, like beer or like soda pop, or even sparkling water. That means that it contains dissolved carbon dioxide, which is kept under pressure and thus stays dissolved. If the pressure is removed, the gas comes out of solution and forms bubbles.Blocking the escape of the gas will prevent more gas from coming out of solution.

Your unusual question sounds like a good one for the Urban Legends website www.snopes.com">snopes

However, I couldn't find it there, so I searched google for: champagne bottle neck spoon And got lots of hits. This was the first one:

standford.edu

I'll let you check it out. Here you have part of it:

"Can a bottle uncorked at midnight still keep its sparkle if some of the wine is saved for another day?

French folk wisdom, which ought to know about these things, prescribes a silver spoon. Hang the spoon, handle down, in the neck of the bottle, store it in the refrigerator, and the champagne is still bubbly days later.

Or so the legend goes. When a team of Stanford researchers put the idea to the test - all in a thirst for knowledge, and digging into their own pockets for research funds - they found that the spoon theory falls flat. In their test, with admittedly preliminary results, the big question about keeping champagne from going flat turns out to be whether or not to use a cork."