Chambord Gambit

In this game, Black lures White into believing that he has the upper hand, but Black has something else in mind.

1. d4, d5
2. c4, e5
3. e3, exd4
4. exd4, Nf6
5. Bg5, Be6
6. cxd5, Bxd5
7. Nc3, Nc6
8. Nxd5, Qxd5
9. Bxf6 ....

White is led to believe that Black would have a double-pawn.  Black's next move surprises him.

9. .... Bb4+
10. Ke2, Qe4 mate.