TestEffect

public ScriptName()
{
    this.BindConsoleCommand("TestEffect", this.Command_TestEffect);
}

private void Command_TestEffect(ParameterCollection args)
{
    string effectName = args[0];
    Vector3 position = Game.LocalPlayer.Character.GetBonePosition(Bone.Head);

    int effect = GTA.Native.Function.Call<int>("START_PTFX", effectName, position.X, position.Y, position.Z, 0f, 0f, 0f, 1f);
}

// Like this in console:
// TestEffect ambient_flies_sparked