I wasn’t aware any pawn “guarded” the king side bishop in the opening position, so I learned something.
Alex Relyea
It is also notable that the first two moves can be interchanged - and it doesn’t only have to be f2-f3. The pawn move f2-f4 doesn’t change anything. Same with black’s advance of the e-pawn - it could be e7-e6 as well as e7-e5. So 1.f4 e5 2.g4?? Qh4#
But the “Fool’s Mate” as it is known requires your opponent to make the worst moves possible in the opening. You yourself have no control over making that happen.
Those two Kings touching was a bit risque at the beginning!
Interesting that this almost always demonstrated with f2-f3 as the first move. I think that g2-g4 is the more likely first move IRL. (I have seen this mate in simuls.)
There’s just some odd harmony to have the pawns on f3 & g4 vs. f4 & g4. Maybe because it is connected pawns self mate? 
On the other hand, there are literally thousands of master level games that have started with the moves 1.f4 e5 (From Gambit versus the Bird’s Opening). The same cannot be said for 1.f3. Of course, of those thousands of laster level games after 1.f4 e5 you will find no examples of 2.g4?? Qh4#
An online program called flashChess III actually does, on its most advanced level, periodically play 1. f3 e5 2.g4, believe it or not.
I like this version:
- P-K3 PKB4!? (Black takes control of Whites K4 Square) 2. B-K2! (Sets a diabolical trap with the important positional plus that whites queen can still support the advance of her queen pawn) P-KN4 (A positional error; Relatively best is P-KR3 with an equal game). B-R5 mate!
Some of you may have difficulty with the notation. Set-up a board without the algebraic grid and you should be able to figure it out.
Doesn’t P-KR3 still have a little bitty problem with B-R5+ P-KN3, BxP mate.
I have a sneaking suspicion you already knew that and were waiting for a comment.
Relatively best pawn move is 2…P-KN3. 2…P-KR3 merely delays the mate by one move. I would probably play 2…N-KB3, which is, IMHO, at least as good as 2…P-KN3.
It’s still “relatively best” because it staves off mate for one more move. 
Bill Smythe
I’m sure this was offered in jest. Since 2…P-KN3 ‘staves off mate’ for far more than one move, I suspect that, in an actual game, I would consider that ‘completely’ better than 2…P-KR3??.
In fact, 2…P-KR3 strikes me as the answer to ‘helpmate in 2’ from the position prior to that move.
Probably the most commonly cited early in the game helpmate is after 1.e4 e5 2.Qh5 helpmate in 1 is now 2…Ke7(!) 3.Qxe5# (or, for our descriptive neanderthal friends, 1.P-K4 P-K4 2.Q-R5 K-K2 3.QxKP#).