Is this a known move?... or am I clever?

Playing a rated match game here on chess.com, I found a cool piece sacrifice on move 8, over-the-board. I've never seen it in any opening book, and can't find it in the usual online resources.

Is this move already known, or am I clever (or both)?

So... my piece sac on move 8: already known, or inspiration?

Your opponent was lost way before but this is not the funny aspect of this game. The entertaining facet is the likelihood of your elo or whatever points are given or taken away from you, to increase significantly enough after such a game, as to constitute an indicative portion of your playing ability, competence you can then lean on in the future, when facing much stronger opponents. Nice.

I checked my database for the position:

Bxc4 is the most common move in the position, first time seen in 1981.

Although as leklerk1 says, your position is quite winning, after black takes cd, white scores over 90% in a sample size of 60 games - which is quite ridiculous - meaning that the line completely busted for black. It is a bad score to get a draw here. 

Your opponent played a dubious move on move one and a horrible one on move 4, but it was good of you to see the refutation.

The only move that makes sense really is e6, other than that, Nc6 is not that bad after Nf3 as after d4 followed by c4.

@blueemu - When did you play this game? I don't see any games since 2014 in your archive and can't find this game anywhere.

4. ... dxc4 ?? -/+ 

It is suspicious on "general principles" (releases tension, gives up centre, gives mobility to White's QP, does nothing to develop his pieces or contest the centre, seems to have no definite plan of development or attack behind it).

It is provably bad by calculating exact lines of play.

8.  Bxc4 is  known theory. 

Well done in finding this and the rest of the refutation for yourself.

Unless someone can prove it that she's not been playing against an engine as Black you are right. She's been proving something else actually.

For the last two years (since August 2014) I have been away from chess.com, helping the Canadian Army improve their training methods... my unit was responsible for creating all the 3D content for the Army's virtual reality training simulators, among other tasks.

So I haven't played since 2014, correct. I'm pretty sure the game was played on this website, though, so it should be there somewhere.

Chess.com never accumulated all of the user games on the website into a database. It could be that the game may not and may never be in the opening explorer.

Move 8 is book move, according to my Hiarcs program. dxc4 is practically a forced loss and e6 is correct.

Not looking at Opening Explorer, looking at his game archive, but I found it. 

It is this one:

https://www.chess.com/daily/game/61959468?page=1

A nice win over a 1963 (at the time) for blueemu.

Thanks. I'm not a premium member, so I can't search my own game archive.

Neither am I, on v3 you can see it.