It could not be simpler. Remember the protagonist in Walker Percy's extraordinary Love in the Ruins who lived on them? Dr. Tom More. His brain was constantly fizzing and fizzling.
There's also the Royal Gin Fizz (with an egg), and, of course, the Sloe Gin Fizz if you can find any Sloe Gin around - or any loose Sloes to soak in your gin. Looks like a Beach Plum. Cape Cod Beach Plums would probably work just fine. They are bitter, flavor-packed wild plums. Maybe I will give that a try.
Photo is the Royal.
nb: Some old comments below from our late pal Marianne Matthews. Miss her.