Press [Ctrl] + [Shift] + C during game play to display the console window. Enter boolProp testingCheatsEnabled true to activate testing cheats mode. This is a very powerful cheat that enables many new things. In Create A Sim, after enabling this code, go into debugmode by pressing [Shift] + N before making a Sim. You now have the following new things in Create A Sim: skin tones, clothing, and some other options such as viewing the skinfilenames. In the game itself, after enabling this code, hold [Shift] and left click on a Sim to have lots of options, such as changing clothes, make your Sim fat or thin, set their aspiration level, etc. This code also can spawn some interesting items, such as the tombstone of L(ife) and D(eath), and family members.

Be careful when using the "Testing cheats mode". Many glitches can occur, such as blocky/scattered picture, being unable to save, return to neighborhood, or quit. In rare cases if you use the code too much, you can lose the ability to travel to community lots. The car/taxi will drive offscreen, then immediately drive back.