Preventing the development of the bishop on c4.
1. e2e4  1... c7c5  2. g1f3  2... d7d6  3. d2d4  3... c5d4  4. f3d4  4... g8f6  5. b1c3  5... a7a6  6. f2f4 This old move still has some venom, it seems. 6... e7e5  7. d4f3  7... b8d7  8. a2a4 