Sim may become sad or angry when they don't have any moodlets.
Sim may scream out in fury if something bad happens to a nearby Sim.
Sim will always have the ability to complain about something. And will give them the positive "Let off Steam" moodlet when doing so.
Sims with the Grumpy trait can develop the "Out of Sorts" moodlet upon awakening. The "Out of Sorts" moodlet gives -20 points to your mood, and it typically last 23 hours. The "Out of Sorts" moodlet occurs at random. Getting a good night’s rest or, for Sims with the Martial Arts skill, meditating can help to alleviate The "Out of Sorts" moodlet much faster.