While Cmar’s mod works as a static nude mod, to actually use the "Erection" states or play with the object, you need an adult gameplay overhaul. The two most popular are (massive, complex simulation) and Passion (lighter, animation-focused). These frameworks hook into the penis script to apply the "Hard" texture and animations.
Click on the NRaas settings options (or use an in-game computer/town hall). Set the to 10,000 . the sims 3 penis mod 1 top