In a recent game of speed chess at chessgames.com, I won quickly with a double check. My opponent was Forplaying of France who played black. Here are the moves of the game along with my commentary:
1. e4 e5
2. Nf3 d5
Black's reply is a surprise. More common moves are Nc6, Nf6 and d6.
3. exd e4
This move is also a surprise. I expect Qxd5 but black attacks my king knight instead.
4. Qe2 Nf6
I pin black's e-pawn.
5. Nc3 Bg4
Black pins my king knight.
6. Nxe4 Bxf3
Black makes a bad move. It is necessary to shield the king from a check on the e-file. This can be accomplished with a move such as Be7 or Qe7. My queen is attacked, so black probably expects me to play Qxf3. But I see that I have a better move.
This is not only a double check but also checkmate. My queen checks on the e-file and my knight checks from f6. The black king has no escape square.
In this game, my opponent surprises me with his second and third moves. He plays aggressively but fails to protect his king. I can ignore the attack on my queen because the black king is vulnerable. My ability to exploit this vulnerability of the black king leads to victory.