With no warning my mom sims died of laughter. I am so mad.

"DeKay;c-17358362" wrote:
This is a tricky one. If you have too many happy moodlets that are boosts, it will make one playful moodlet affect all of them and thus, making the sim hysterical.

I've had this issue in some of my more prosperous households. The Sims are always so happy from high needs and nice surroundings moodlets that a toddler telling them a joke sends them into Very Playful. I keep an eye on the background colors for my Sims' icons and if anyone goes that pinky-purple color, I send them off to a mirror or to take a nap.

Moodlets used to be worse, but they changed them up a little. When Sims 4 first came out, moods flashed back and forth a lot. I don't like the mood deaths much, but it's so hard to die on accident in Sims 4 that I can't really complain.