It's real name is the "Duras Gambit," where the term "Fred Defence" came from is unknown. It was played by Oldřich Duras. I've played it, with some success. Even what's known as the "Southern Fred" with 1.e4 1.f5 2.exf5 followed by 2.Kf7. I think some random guy called Fred played it sometimes, and wasn't a very good chess player himself.
Fred Defense(1.e4 f5)
I've heard "The Fred" used for various (poor) openings. It might be a reference to Fred Flintstone or just figuring that Fred sounds like a name for an average Joe who wasn't particularly knowledgeable (at least for people that never heard of Fred Reinfeld).
The first "Fred" I heard of involved Black playing f6 and Kf7.
Its pure nonsense. take the pawn, play d4 and bd3. white can choose between nf3-nh4, or ne2-ng3 to hold unto the pawn if need be. (in some lines, early qf3 is also possible).
black simply cant play it like a king's gambit because he is too slow to threaten a central pawn majority