While playing the game, press Up, Down, Left, Right, Square, Up, Down, Circle, Up.
No sound or notification will occur. But if you press "R" nitro will come out.
Rush Hints, Tips, Tricks, Secrets, & Glitches
How To Get Rid Of Cops
If you have cops on your tail and you can't lose them try this. First the cops will be chasing you (obviously) next get onto a 2 lane highway. Then turn into the oncoming traffic lane. The cops might try to follow you but they will hit the oncoming cars. After that all you have to worry about is not hitting the oncoming traffic yourself!