This is a game where I am White (I am playing a blitz game). Black played Ng4, and I carelessly responded with Nc2? (the losing move).
How can Black force the win of a pawn, and also gain a winning attack at the same time? Hint: The Ng4 move had a very simple threat.
After losing this game, I studied the opening pretty carefully and I learned quite a bit about this Ng4 move. It turns out that when Black plays Ng4, white should immediately play h3! (I was worried about Qb6 after h3, but that is the main line). This is a good example of why blitz can be incredibly helpful in learning openings.