@aodohertyAhh, hysteria, my old friend. :P We used SO MANY DEATH FLOWERS before I used MC Command Center to disable emotional deaths. And yes, it was sentiments; my Sim had positive sentiments with her daughter that gave her a playful buff and she's Cheerful.
Here are some of the strategies that I successfully used.
- Talk yourself down in the mirror
- Start a club gathering with a different emotional tone (strongest focused vibe, strongest inspired vibe, etc.)
- Eat a Jungle Adventure Tree of Emotions berry
- Drink any cowplant milk that isn't happy or playful
- Get eaten by a cowplant (okay, this is extreme and you can't do it two days in a row or you'll die)
Lately I've been using Meaningful Stories, a mod that redesigns the emotion system so that you can't get hysterical just from being near a friend in a comfy chair and a nicely decorated room. It's harder to get your Sim into the mood you want them to be in, but they don't die from hanging around with their family. It does a lot more and may or may not be your cup of tea. But the issue is, IMHO, that there are so many happy buffs handed out by so many things (and don't get me wrong, I love happy Sims!) that a single playful buff sends them over the edge into Hysteria and death.
When my Sim and her daughter lived in a Tiny House together, my Sim's daughter was working on the Joke Star aspiration and her mother had Vicarious, so if I let her mother sit next to her while she was writing comedy routines, Mom would gain comedy skill but also become Hysterical. *facepalm*
And yes, as others have said, that's a Base Game Sentiment.