Trapped by this strange opening line, how to proceed? I play this kid that does strange things in the game. I thought in this following game that he was using the Pirc defense as Black, when it opened 1.d4 d6 2.e4 Nf6 3.Nc3. Then he goes off with 3...d5. It seems that I get trapped by this kind of (to me) irrational thing. Any advice on how best to proceed?

[FEN ""]
1. d4 d6 2. e4 Nf6 3. Nc3 d5
I have never seen this idea before, but it is not as stupid as it looks.

There are basically three options for white:


Play the Veresov, i.e. 4.f3. In that case black will argue that he has the black side of a Caro-Kann-Fantasy variation and that he will at one point play c5 in one move, regaining the tempo lost with d6-d5. 
Play exd5. In that case black will say that he has a Scandinavian defense and that compared to the line 1.e4 d5 2.ed Nf6 3.Nf3 Nxd5 there is no 4.c4 kicking the knight from d5 and establishing a nice space advantage.
Play e5. In that case black will probably play 4...Ne4 and you can try to be tricky with 5.Nce2, trying to catch the knight with f3. Taking the knight directly with 5.Nxe4 is also possible, but there is probably no way to quickly assault the weak pawn on e4. 


I think 4.e5 is the most principled option, but it is no refutation. You'll get a very complicated fight were the most you can hope for is that your opponent has to be more careful than you.