OMG! I LOVE THAT CHEAT!! It has saved many of my sim's lives (except the one I killed with a sattelite. Oh, and the one that died by flies. And the one that got electrocuted . . .)
I type in "boolProp testingcheatsenabled true" (minus quotation marks)
I also use the StretchSkeleton one. It is seriously funny.
1.0 is the normal size, so if you want a tall sim you type in the cheats bar "StretchSkeleton 1.1" (or any other size you wish) and they will s t r e t c h. For a shorter one, "StretchSkeleton 0.9"
Once I made a Jacob and he was 1.5 . . . very, very tall. Him kissing people was sooo funny.