What is a pony champagne bottle?

A "pony champagne bottle" isn't a standard term in the wine or beverage industry. It's likely a slang term or a regional expression.

Here's why:

* Champagne bottles have standard sizes: The most common sizes are:

* Standard: 750ml (about 25 oz)

* Magnum: 1.5L (about 50 oz)

* Jeroboam: 3L (about 100 oz)

* Rehoboam: 4.5L (about 150 oz)

* "Pony" often refers to small amounts: In some contexts, "pony" refers to a small drink, like a pony of beer (about 6 oz).

Possible Interpretations:

* A small champagne bottle: It could be a slang term for a smaller size than a standard bottle, perhaps a 375 ml (half-bottle) or a smaller, non-standard size.

* A specific brand or type: It might be a unique product or a brand name used for a specific bottle style.

To get a clearer answer, you'd need more context.

If you could provide more information about where you heard the term, who used it, or what they were referring to, it would be easier to understand what they meant.