e4 e5 nf3 f6!!??

Fun for White obviously after 4. Nc4. If 4...Qxe4+ 5. Ne3 followed by 6. Nc3, if 4...d5 5. Qh5+ followed by 6. Qxd5, and if 4...f5 5. Nc3 and then if 5...fxe4? 6. Nd5.
Actually I suppose in that second line Black gets some counterplay as follows - is this what you are hoping for?

nope not worst look at the opening of the day the mosquitto gambit which is the worst in my oppinion

the real reason f6 is a bad move is much simpler. It doesnt develop.
d6 doesn't develop either.

wow great post. I have been playing 2...f6 all these years, and facing it all the time! Everyone plays it.
What a brilliant refutation!

the real reason f6 is a bad move is much simpler. It doesnt develop.
d6 doesn't develop either.
But d6 is a more solid way to defend the pawn, because it doesn't weaken the kingside, and in general it begins to set up a solid position. 2...d6 isn't necessarily the best line (and in my opinion going through a Pirc-like move order is a better option to get to a Philidor), but it's loads more preferable than 2...f6? and much more sound.
The real real real issue is that f6 doesn't actually defend the pawn. It opens up tactics that allow White to take on e5 anyway. The pawn on e5 is only indirectly defended by playing Qe7 and retaking on e4--something Black could do without playing f6 anyway.

I can't believe I am going to say this but I believe Fisher played it wrong. The one time someone played 3...Qe7 I played as fisher did except I played Be3. The light square bishop is to valuable as an attacking piece to be tied down to e2. Bishop e3 also prevents the next threat. I will break out the board and check it out. This is from memory.
Not the worst opening at all!! Here comes the best game of Damiano defense!! Why is it the best game? Because Worlds best player got drawn by the Damiano defense. Recently I am trying this opening. Good progress!!
Worst opening ever in my opinion for black. Here's why.