1.Nf3 f6 2.Nd4 Nh6 3.e3 Ng4 4.f4 c6

White can play 5.Nf5 e6 6.Nxg7.

Other possible lines:

5.Nc3 e5,

5.Nb5 Qa5 (or 5...cxb5 6.Nc3 d5 7.Nb5 Qa5 8.b4 Qxb4 9.Bb5 Nc6) 6.c3 Nf2 7.Qh5 g6 8.Nxc7 Kd8.