If you're going to play an opening as sharp as the King's Gambit, you'd better know what you're doing. If not, you might just lose the shortest game of a Chess Olympiad (see below). After 3...Qh4+, White is losing at least a rook, after 4.g3 Qxe4+ 5.Qe2(!) Qxh1.
Incidentally, I once saw a tournament game where Black played 1.e4 e5 2.f4 Nc6!? (unusual, but playable; one idea is the countergambit 3.Nf3 f5!? invented by Miles). Now White innocently played 3.fxe5?? and Black just as innocently responded 3...Nxe5??, missing the crushing 3...Qh4+!
ADDENDUM: Incredibly, it seems that after 2...Nc6 3.fxe5??,
over 80% of players have played 3...Nxe5??