Secret skill

There are several secret skills in The Sims 2.

Yoga
Sims who have three or more Body points get the "Do Yoga" self-interaction. Yoga is not only a skill in its own right, but doing yoga builds fitness and Body skill.

Painting
The more paintings a sim paints, the more he will be paid for them--even if (especially if) he has already maxed his Creativity.

Meditation
Meditation is a skill that Sims from teens on up acquire if they have sufficient Logic points. While a Sim meditates, their motives; such as Energy or Hunger do not decay. If you have your Sims meditate for a certain amount of time, they could learn to teleport.

Dancing
This is a hidden skill that involves sims getting better at the activity of dancing. Sims who are at the bottom end of the skill have very entertaining actions and moves. Teen sims that get to the top of the dancing skill can qualify for the Tsang Footwork Scholarship (University required).

Pool
A skill learned by playing pool/billiards. Teens can receive the Phelps-Wilsonoff Billiards Prize of §1000 for having a high pool skill (University required).