Below is a patch to remove the censor which you see when a Sim steps into a shower or sits on a toilet.
This patch was made by CyberOps and is posted here with permission: Censor patch
Place this file in C:\Program Files\Electronic Arts\The Sims 3\Mods\Packages (or D or E or wherever you have your game installed).
The patch is safe to use. If you want your censor back, just remove the patch.
Above patch works for every game version, no matter what pack is installed. However, it is adviced to use an updated patch if you have a certain pack installed as some special effects like bathbubbels will be removed as well.
For World Adventures and High-end Loft: Mod The Sims
For Ambitions: Mod The Sims
If you want your sims to have realistic nude skins, go to Sexy Sims.