Don't ever play this opening. It is just bad.
Diamiono Defence

KORRECTSHUN: It's the DAMIANO Defense, NOT Diamiono!
careful here we don't want to scare the kid away. (c;
This is probably one of the worst openings for black and should never be played, and at this point if white takes the pawn you should not accept it instead you play your queen to e7 still that leaves white ahead on development but at least you do not go down the exchange or into the mating lines.

what !? I got two different opinion here one is say ok for black and the other say is bad for black ?!
Actually I did a little reserach on this opening just now, and found a game that included bobby fischer as the white pieces and only managing to gain a draw from this opening.

what !? I got two different opinion here one is say ok for black and the other say is bad for black ?!
There's no question it's bad for black. I wanted to find that Fischer game where he only drew, but gave up after a very brief google search.
1. Someone bad enough to play 2.f6 will very likely be bad enough to also take the knight.
2. If black doesn't take the knight he still gets a bad game.
3. It is fun to point out Fischer only drew, but I forget if this was a simul or maybe a young Bobby? In any case it doesn't change the fact that 2.f6 is bad.

If I played against this in a club, I would undoubtedly take the pawn.
If I saw this at a tournament though, being the safety first kinda guy I am, I would be very tempted to play either 3.d4 or 3.Bc4 and let the drawbacks of a move like f6 speak for itself without needing any direct punishment.
Assuming my tournament opponent isn't rated 800 that is

Currently I am involved with a thematic tournament with the featured opening of Damano's Defence.
It is just over 1/2 over and the games have been surprising hard to win, from the Black side of course! ;)
Nevetherless, here is the link to the tournament:
http://www.chess.com/tournament/thematic---damiano-defence
I have also collected over 100 games of this opening for study (and pleasure).
Please see my website, www.TheNewChessPlayer.com
Click on the opening button and then on the king pawn games. You'll be able to download the PDF file.
Hope this helps!
barefoot_player.

It's amazing how many people think that Nxe5 is a refutation. As rightly pointed out by Ajedrecito Bc4! is a much stronger reply.

F6 is bad.
Don't play bad moves, m-kay?
Well, ...f6 is bad, mmmkay? But mmmkay is spelled mmmkay, not m-kay, mmmkay?
mmmkay
3. Nxe5! is at least equally good to 3. Bc4 IMO, as white will end up ahead in development anyways. 3... Qe7! 4. N(somewhere) Qxe4+ 5.Bd2 followed by 6. Nc3 , and white has three pieces developed to black's one. That, and black's weak kingside, is more than enough to ensure an advantage to white.
3. Bc4 also gets a lead in development, but the point of 3. Nxe5 is that it proves that 2...f6 was useless.
Also, @DaBigOne: I think 4... d5?! is way too early. White can play 5. d3 or 5. Nc3, holding the pawn without any trouble and developing even faster.
This is the Diamiono Defence. After f6? 3.Nxe5! is a great move, because after 3.fxe5 4.Qh5+, White will lose a rook because of g6, or be unable to castle, and White having attacking oppurtunities.