During gameplay quickly press Down, L, Z, R, Left, X. If you have entered the code correctly you will hear a Sim voice as confirmation. A blue gnome will then appear near the house that your Sim is at and your Sim will get a phone call each day to receive Simoleons. This also happens when they visit another house (except Mom's) and in order to get the Simoleons there you have to force the Sim that is hosting you as a visitor to answer the phone by walking near it.
Added by: Sanzano Sep 14th 2012, ID#9495