Press Back or press Jump + D-pad to perform special moves.
You can get a lot more points if you dive to the left and catch the disc.
It is more difficult, but can earn much more points.
Note: This trick requires a controller with a turbo feature.
Begin a BMX race and intentionally move slowly.
Hold B while turbo is enabled to quickly bounce the bike up and down to accumulate points.
Press Select to quickly stop your bike.