...f5 is the Fred Defense to the king's pawn opening, and it is generally considered to be rather weak.
I kinda invented it

I know this as the Duras Gambit, but the posts above me are correct... black sacrifices a pawn for absolutely no compensation. In fact, it's WHITE that gets the positional bonus.
I don't know the name of this one, but I've never seen it. It's strange, I know but not losing. You can get the pawn back, and you develop things. But BE CAREFUL if you're doing this because there's a tiny difference between winning and losing. Don't flame.
Comments? *dies*