4. f4, Bg7
5. Nf3, c5
6. dxc5, Qa5
7. Bb5+, Bd7
8. Qe2, Nxe4
9. Bxd7+, Nxd7
10. Qxe4, Bxc3+
the normal move is Bd3 and after black captures the c-pawn play Qe2 and Be3 to drive the queen away. If all that seems a bit slow for your taste then you can leave the black c-pawn and play Bb5+ at move 6.; that can get quite fierce!