So.. backstory, in Salient Facts, Somewhat Condensed Version:
53 Hours Ago
2 cats arrive in my home. They're ~7 months old, and have been in a foster home, and lived most of their life in a room with no "human type things" such as, in this case, plumbing (which will become relevant shortly). They immediately hide between outer and inner shower curtains and stay there for ~24 hours straight except for litterbox trips. It may be important to note that for the entire time they are in this bathroom, the toilet lid is closed.
25 Hours Ago
Cat A (they don't have names yet, and I need a shorter nomenclature than constantly typing "the male cat, that is slightly bigger and more sociable and purrs louder") comes out of his shell long enough to actually check the place out a bit, and be friendly. Cat B switches to hiding under the bed. I am relieved, because at least this means I can have a shower in the morning without taking the risk of a wet furry ball with sharp claws sticking out at 4 points having an unfortunate encounter with my calves.
3 Hours Ago
Both Cat A and, eventually, Cat B, come out from under the bed, are petted, play with toys, hang out in the living room, and start to feel more comfortable around the place. Cat A still far more sociable and will actually jump on my lap (and on my keyboard while typing, because, apparently, Cat A logic goes like this: "hands are for petting me, hands are on keyboard, therefore I should be on keyboard").
20 Minutes Ago
Cat A departs to go hang out in the bedroom doorway. Cat B chillin' on the coffee table.
5 Minutes Ago
I have to go to the bathroom. As I pass the aforementioned bedroom doorway, Cat A shies back a bit, so I reach down and pet him so he learns that "people walking by, just because they're big, doesn't mean they're scary". Apparently mollified by this, he purrs and follows me into the bathroom.
I see Cat A walking beside me, checking out the spot by the toilet where his litterbox used to be (it has been moved: Tile floors and cat litter don't mix well with bare feet, and they're comfortable out of the bathroom now).
I reach for the toilet lid to raise it. A distant part of my brain notes that the cat is heading that direction, but it's probably ok because he's just checking out the ex-litterbox-spot.
I start raising the lid. That part of my brain notices Cat A's legs hunching up, and recalls seeing specks of cat litter on the lid indicating that yes, at least one cat has previously jumped up there and walked across it. It is too late to stop the inertia of either hand or cat, though. Nerve impulses don't even travel that fast down an arm that long.
Lid hits the back of the toilet. Cat A reaches the apex of his jump. Probably some feline synapse is firing in his brain saying "hey, this looks slightly different up here than it did last time...! Alert! Alert!"
Cat A enters panic mode, engages all limbs and claws simultaneously. Looks a bit like a roll of dough trying to spontaneously turn itself into a pretzel, then changing its mind. The water wasn't deep, pretty sure there is no wet cat above any of his 4 shoulders, except perhaps a bit of his belly, but let's face it, details like this are hardly reassuring to a feline involved in this particular situation.
Cat A exceeds escape velocity of the toilet bowl. Runs straight out of the room and into the bathroom.
I burst out in the largest string of laughter I've had for a while. This scares Cat B, who subsequently hides behind the couch.
I finally stop laughing long enough to describe this situation to a friend who happened to be online. We share a laugh. She relates a similar story that happened to her cat, but at a time when her daughter was young enough that she didn't always flush, for extra trauma.
I go to check on Cat A. I lift up an edge of the comforter to see which side of the bed he is under. He is right there. He hisses at me (first time ever!). Cat A seems to have taken this personally.
And yet, despite the fact that I feel just a speck guilty because part of my brain saw that coming the instant he followed me into the bathroom, I still think it is hilarious and I do not regret my actions! I'm not a crook! </nixon>. But yes, this may make me a terrible person.
I hope Cat A forgives me someday. At the very least, I'm pretty sure this incident has undone 53 hours of "friendliness conditioning" and may lead to therapy (for him or me, yet to be determined).