There is nothing we take for granted as much as sanity. No matter what "crazy" unexpected thing might happen at the office tomorrow, you still know that you're not going to show up and find, say, your boss replaced by a talking guitar.
But as we have explored before, there are mental disorders that can mess with your perception of reality in unimaginable ways, while often leaving the rest of your mind untouched.
Disorders like ...
Imagine you get into an argument with your asshole roommate about the unpaid rent. You need to let off some steam, so you call your girlfriend to see if she wants to go for a nice burrito somewhere, but for some reason it's your asshole roommate on the end of the line and he's calling you "honey." So you hang up and go outside, but your asshole roommate is waving at you from the neighbor's yard.
Apparently Mr. Moneybags has enough cash for two rents.
Furious, you go to the local bar, only to find that your asshole roommate is the one pouring the drinks. Ten minutes and two black eyes later, you find yourself getting arrested by your asshole roommate.
Fregoli syndrome is the delusion that some or all of the people you meet during the course of a day are actually the same person. It's named after a famous actor who was able to change costumes rapidly onstage. As you would expect, Fregoli sufferers are frequently paranoid, as they reasonably assume that some master of disguise is fucking with them. Or maybe some kind of shape-shifting wizard.
Keep practicing, buddy. You can be James Hetfield, but you can't be all of Metallica.
The disorder comes with different degrees of severity, though. Sometimes, sufferers don't know exactly who is stalking them, but everybody looks really familiar somehow. It's like waking up to find your town populated entirely by people who went to your high school that you never spoke to much. One guy was known to just walk up to everybody and ask where they'd met before.
Fregoli syndrome also makes for an interesting insanity stew when it tag-teams with other disorders. For instance, a woman who was diagnosed with the condition also suffered from schizophrenia and something called erotomania, the belief that someone is in love with you when they aren't. She believed that actor Erik Estrada was in love with her, communicated with her telepathically and disguised himself to show up in her daily life in the form of her acquaintances and current boyfriend.
This is someone's fantasy.
It's such a sad story that we're hoping someday it will turn out she was right all along, and Mr. Estrada will be arrested.
You wake up in the middle of the night and shuffle down the hall to the bathroom. You stumble in and flick on the light, and look up at the mirror on the medicine cabinet over your sink.
A stranger is standing there. He's staring right at you, as surprised to see you as you are to see him. You scream, "Get the hell out of my bathroom, you pervert! Go look at someone else's dick!" but the man only screams your own words back at you.
"Bring it on, buddy, I can do this all day."
People suffering from a disorder called mirrored-self misidentification have a breakdown with the part of their brain that understands how reflections work, so when they look at a mirror, their brain tells them they're looking at a stranger through a window. On a rational level, they understand what mirrors are and what they do, but they maintain the strong impression that their reflection is some nefarious doppelganger. It shows up mostly in Alzheimer's patients, but even then it's rare.
Scientists study the disorder by presenting subjects with a mirror, then holding up an object behind them and asking them to grab it. People without the disorder will turn around and reach for the object behind them, but someone who suffers from the condition tries to reach through the mirror, providing hours of quality entertainment for the researchers.
"You guys are DICKS!
One patient known as TH described the man in his mirror as "a dead ringer" for himself. He would even try to talk to his reflection, though their conversations were a little one-sided. TH did not particularly dislike this person, saying he had no reason to be suspicious of him. He believed that this man lived in the apartment adjoining his own. (There was no apartment adjoining his own.)
And they liked to look at each other while masturbating.