I mostly use Fanny Fanakapan when referring to someone whose name I cant think of quickly, don't know or just a name to use.    I dont use it to attract someones attention. as people always comment when I say it here in Australia   I can use it when referring to someone I'm not partial too but not often.    I have never heard of it as Fred Fanakapan. Fanny has been with me for 62 years (60 living in Australia from London, England).