The Sims 3
50 Achievements
1,000
30-35h
Be Excellent To Each-other
Reached the maximum potential Karma.
15
How to unlock the Be Excellent To Each-other achievement in The Sims 3 - Definitive Guide
The maximum potential Karma is 100. Karma is earned by completeting wishes and when the clock strikes midnight. You will earn 1 point for each wish you complete and you will earn anywhere from 8-15 points when it turns to midnight. As long as you don't use Karma powers for a couple of days you'll get this trophy easily. You can check how many Karma points you have by pushing and going over to the Karma menu.
Right at the beginning of the game when you first move in to your house you start with 80/100 karma. Simply don't use any karma powers for about two days. Every night at Midnight you will receive 0-15 karma depending mainly on your mood. You will also receive 1 karma point for each wish you fulfill. This shouldn't take you long at all.