Queen's gambit trap

1.d4 d5

2.c4 e6

3.Nc3 Nf6

4.Bg5 Nbd7

5.cxd5 exd5

6.Nxd5?? Nxd5!!

7.Bxd8 Bb4+

8.Qd2 Bxd2+

9.Kxd2 Kxd8!

0-1

After move 5.exd5 your opponent would think "I can capture this pawn plus I am pinning his knight, he will play Be7 and we will trade two minor pieces." That is blunder. After that you play an stunning move Nxd5 giving your fatty queen. He will think "That is a free fatty queen" and then we play Bb4+ and the forced move for white is Qd2. After that trade we play an great move Kxd8 and we have one more minor piece, so it doesn't matter that he has one more pawn (we have +2 in materials).