When did Operation Flipper happen?

There is no known historical operation or event called "Operation Flipper". It's possible you're thinking of a different operation or have a typo.

Could you please provide more context or details about what you're looking for? For example:

* What kind of operation was it? (military, espionage, humanitarian, etc.)

* When and where did it occur?

* Who was involved?

* What was its purpose?

With more information, I can try to help you find what you're looking for.