ever had a case where you play an opening and accidentally have it transpose into an opening that your opponent knows better than you?
eg: (of course I'm white!)
[Event "rated standard match"]
[Site "freechess.org"]
[Date "2006.10.24"]
[Round "?"]
[White "Xpoint"]
[Black "EvilDuck"]
[Result "1-0"]
[ECO "B32"]
1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 d6 5. Nc3 Nf6 6. Bc4 (wasn't sure of the best move, so went with "what would Fischer do?"😉 g6 (looks like we can go into the Dragon) 7. Be3 Bg7 8.
f3 O-O 9. Qd2 (and it's a Yugoslav Attack!) Re8 10. O-O-O Ne5 11. Bb3 a6 (Black doesn't understand the Yugoslav enough to realize that he will need more than a pawn storm to base his attack off of) 12. Bh6 Bh8 13. Kb1 b5 14. h4 Bb7 (I personally don't like Bb7 as it seems to point the Bishop in the wrong direction)
15. h5 Nc4 16. Bxc4 bxc4 17. Nf5 e6? 18. Nxd6 Re7 19. hxg6 fxg6 20. Bg5 Rd7
21. e5 Rxd6 22. exd6 Qd7 23. Bxf6 Bxf6 24. Qf4 Rf8 25. Qxc4 Rc8 26. Ne4! Bg7
27. Nc5 Bd5? 28. Qxd5 exd5 29. Nxd7 {EvilDuck resigns} 1-0
blunders aside, black played into an opening (and a very very sharp one too) that he didn't understand and it cost him.