Social

Sims crave other Sims, especially if they are Outgoing. Sharing a meal with a family member, hopping into the hot tub with some friends, or catching up with a neighbor are some simple ways of making sure the Social metre doesn’t drop into the red. Interacting with other Sims usually boost the bar, but sometimes it doesn’t; if you have a negative conversation, for example, or come on too strong (flirting where it isn't welcome), your Social rating will drop. Also, fighting or arguing with a rival won’t do the Social meter any favors either.

Social is also easy to boost in areas such as Old Town and Studio Town. There are plenty of people wandering around to talk to if you need to. Your family goes with you to Vacation Island, so there are plenty of social opportunities there. As for Downtown...well, if you're taking a date along with you, your Social bar shouldn't really be emptying.

Pets
Pets are just as social as Sims, so it is important to play with them regularly and giving them attention. A pet in need of a Social boost will probably try to get your attention. Playing with other pets can also help.

If the Social bar is in the red for too long, your Sim will become mentally ill, which is represented by the appearence of the Social Bunny, an adult-sized NPC bunny that can only be seen by the Sim that summoned it.