Putting a teaspoon handle-down into a bottle of champagne when putting it in the fridge in order to "retain the fizziness" which I did unquestionably as something we just "did", until I had to tell someone else to do it a few months ago and realised that there was no reason this should work and, lo and behold, it makes no difference whatsoever.
I dont think the spoon handle is actually supposed to touch the liquid. That would be hard to achive in a classic bottle of champagne, even if its full, I guess. Teaspoon handles are not that long.
This works for pop/soda. I'm not entirely sure why, but if you pour a glass of coke/pepsi/whatever, and put a steel spoon or fork in the glass, and put it in the fridge, it won't go flat (nearly as quick).