idk I've heard of it tho
Queen Pawn opening w/ Bg5 ...h6 h4

There are probably several positions that have this. This is probably not the one you're thinking of, but here's one at 365chess.com.
I got to try it on chess.com: http://www.chess.com/echess/game?id=106589446
Before deciding on my move, I also read the notes to this game of Kasparov: http://www.chessgames.com/perl/chessgame?gid=1070188
Maybe that's not what you're thinking, but, as I said, there are probably quite a few times where White sacrifices a bishop on g5 in the Queen's Gambit.

There are probably several positions that have this. This is probably not the one you're thinking of, but here's one at 365chess.com.
I got to try it on chess.com: http://www.chess.com/echess/game?id=106589446
Before deciding on my move, I also read the notes to this game of Kasparov: http://www.chessgames.com/perl/chessgame?gid=1070188
Maybe that's not what you're thinking, but, as I said, there are probably quite a few times where White sacrifices a bishop on g5 in the Queen's Gambit.
That looks like a pretty cool line.
It sounds like the Raptor Variation of the Trompowsky Attack after, 1.d4 Nf6 2.Bg5 Ne4 3.h4. It was often played by British GM Julian Hodgson. A timely h6 is used to chase the Bishop away.
http://www.chess.com/opening/eco/A45_Trompowsky_Attack_Raptor_Variation
Edit: I have an old VHS tape (seriously, tape) around here where he covers this variaiton.

There is a line in the Queen's Gambit, known as the Rubinstein Variation, where ...h6 is a mistake because White just has to play h4.
The diagram editor is not working today, so I'm just listing the moves:
1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Be7 5.e3 O-O 6.Nf3 Nbd7 7.Qc2 (as opposed to the more common 7.Rc1) and now 7...h6 is a mistake because of 8.h4, instead Black should play 7...c5 with a roughly equal, though dynamic position.
Many years ago I remember a Chess Life article about a Queen Pawn opening where white plays Bg5 (so it was likely a Veresov, Torre, or Trompovsky). At some point Black played ...h6 and White replied h4. If the bishop was taken, White got an huge attack.
As I recall, the article gave this opening a name, probably after a player who used it. I have not been able to find the article (the online Chess Life archives don't go back far enough), nor can I find a name.
Does anyone know the name?