What is the french 999?

"French 999" is not a standard term in French or English. It is possible you are referring to one of the following:

* A slang term: It's possible "French 999" is a slang term, but without further context, it's impossible to know its meaning.

* A specific product: There may be a product, brand, or item called "French 999." If you can provide more information about the context where you heard this term, I might be able to help you figure out what it refers to.

Please provide more information about where you encountered this term, and I'll do my best to assist you!