Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Bxc6/4...dxc6/5. O-O/5...Bg4

5...Bg4
This aggressive move pins the f3-knight and is a good way to stop the threat of Nxe5. But this also has a hidden sting to it! The 'Obvious' h3 allows a hidden trap!