Nudity - Basics
Sims bodies are divided into 4 parts head-top-bottom-feet and WickedWhims nudity system mostly uses the top and bottom half of the Sim body for undressing purposes.
Currently, WickedWhims doesn’t include general naked body overrides, like detailed skin or defined shapes, so these always have to be downloaded separately. WickedWhims only includes a default penis model that is used for any Sim that is flagged to have a penis.
You can download defined body mods at the Download page.
Any Sim in the game can be flagged as having a penis by editing that Sim in the CAS Screen, in the CAS Gender Settings menu. Penis used by a Sim can be changed using the ‘Body Selector’ and cannot be set using the CAS Screen. In case of any issues, check out the Penis Issues page.
Most basic interactions allow you to undress top, bottom, and feet outfit parts, as well as all of them at once. WickedWhims uses the Special Outfit Category for nudity, but all default nudity interactions in-game (like showering) use the Bathing Outfit Category, which is separate.
Unless disabled in settings, undressing requires Sims to have high enough Naturism or Exhibitionism skill level, depending on the situation. You can read more about that at the Nudity Skills page.