Insane is one of the many traits that your Sim can have in the Sims Social. According to the in-game description:
"Insane Sims may be silly, dangerous or downright bonkers but they're never, ever dull."
Having the full 4 levels of the Insane trait can restore your Sim's Social, Hunger, and Funneeds at no Energy cost, making it almost unnecessary to talk to neighbors to become inspired. Arguably, this is one of the more useful traits because it saves (your energy) and ((time used during trips to visit neighbors) or (time used inviting neighbors over)).
Note that clicking your Sim's social button at other people's houses can cause your Sim to talk to itself instead of interacting with the other Sim.
Cost to Upgrade
Watch for flailing arms.
Sim occasionally waves their hands around and/or makes funny noises.
You see a plant, they see someone to talk to.
Social can be increased by +1 by talking to plants, but requires 1 energy.
You can eat your own shoe!
Self interaction: "Eat own shoe" will increase +1 Hunger level.
Sometimes the best conversation is with yourself.
Self interaction "Talk to self" will increase +1 Social and +1 Fun with no energy cost; can only do this twice in a row; will need to do other actions to allow this again.