Or rather, that you’d last an unusually short time in. And by “last” I don’t mean “give up and want to go home”, I mean die, cease to exist, or otherwise become non-functional in some way (e.g. get mind controlled, turned to stone, shapeshifted into a useless critter). If, like in my example, you’re in a universe that’s inevitably fucked, only list it if you’d be fucked rather quicker than most people.
I’d also prefer if it’s because of an aspect of your personality, no stuff like “I would be killed because they hate black people in this universe” or “my wheelchair would cause the peasants to accuse me of witchcraft.” Maybe if it’s some exceptionally odd prejudice in your given universe you can list it (e.g. a universe where people with scars on their left arm are hanged).
The Cthulhu Mythos (or any similar mythos) I wouldn’t last a day in. The absolute second I found out there was an entire cadre of secrets man just Was Not Meant To Know™, especially secrets that I could gain access relatively easily, without needing to rub elbows with the Illuminati or whatever, my life’s goal would instantly become to know that stuff. Oh sure, I might TELL myself “no, it’s fine. You know what happens to people who research this stuff.” But I know myself too well, and I know I’d give in eventually. Sooner rather than later too.
Any universe where magic is liable to blow up in your face if you experiment with it would probably get me too.
So what universes would you not last a day in? I suspect I’m nowhere near unique in my example, especially on this board, but it’ll be interesting to see what else comes up.