The following codes are for Grand Theft Auto: Vice City for Playstation 2 and can be entered at any time in the game.
You will know the code is entered correctly when a message saying "Cheat Code Activated" appears on the top left of your screen.

Love Fist Limo
R2, Up, L2, Left, Left, R1, L1, Circle, Right.

Mad Cars Cheat (All AI characters drive aggresively)
R2, Circle, R1, L2, Right, R1, L1, R2, L2.

Bikini-clad Women Carry Guns
Right, L1, Circle, L2, Left, X, R1, L1, L1, X.