This testingcheatsenabled cheat allows you to do several useful things when used 
properly. First, hold CTRL+SHIFT+C (CTRL+SHIFT+WindowsKey+C for Vista) and enter 
this code: testingcheatsenabled true

Now, hold SHIFT and click your letterbox. This will provide you with these options:

* Make All Happy 
* Force Visitor 
* Set Career 
* Set level 

You may also hold SHIFT and click on Sims to get these options:

* Add Sim to House 
* Change Sim Traits 
* Force Aging 

Work place
* Force Opportunity
* Force Event
* Force All Events

Any Sim
* Trigger Age Transition
* Modify Traits

Active Sim
* Modify Traits for Active Sim

Non-household Sim
* Add to Household

Moodlet Panel
* Remove a Moodlet from the Moodlet Panel. 
Note: If it is motive induced, the bar related to the negative Moodlet will 
be completely filled.

In Ground View mode, hold SHIFT and click a spot and your Sim will teleport to it.