Other than bodily functions and toilet paper of course. When I was 10, I went to a post wedding dinner. I don't know why, I guess I was just bored, I took a pepper shaker and put it in my pocket. It was of medium size. I went to the restroom, dropped it in the toilet, and kicked the handle. Whoosh...the toilet sucked it down like a Hoover. I was ready to run in case it got stuck. Makes you wonder what kind of massive crap someone has to take to clog a toilet. I flushed a freaking pepper shaker!! And I want to do it again.
On an episode of Dirty Jobs, the guy worked at a waste treatment plant. They must see some weird stuff come out of the pipes.
A pregnancy test, a ring, part of a cell phone, drugs, the tobacco from a cigarillo, a stupid freaking polly pocket, and your mom.
vomit but it terms of strange objects, back in high school i flushed down 2 unopened condoms to hide them from my mom during her monthly room snoops.
Lots of fish. I mean, LOTS of fish. You keep fish for 25 years or so, and even if you know what you're doing (which I did, most of the time) you are gonna lose some fish. Most of those years I had the old style toilets, thank god... the Archie Bunker Specials. Those suckers would take an 8" South American cichlid and holler for more. I've retired from the arena of the aquarium hobbyist, at least for now, but perhaps I'll get back into it someday. With these low-flush toilets, the pansy-ass things, I may have to resort to a landfill.
when I was a kid, a handi snacks wrapper thing. that clogged the toilet and my parents had to get a plumber to unclog it and when they pulled out the evidence and I was busted. That ended my "let's see what can get flushed" experiment at a young age. more than a decade later, I was sleeping with this guy's host-daughter at his place and then he showed up when we thought he was out. I quickly ran to the bathroom to get changed and flush the condom down the toilet, but it wouldn't take and kept on coming back up. They must have thought I had diarrea or something. I ended up taking it back and wrapping it up and kept it in my pocket until i could find a garbage can outside.
Any time you have a situations like that (where the damn thing won't go down) just throw a wad of toilet paper on top of it. Has always done the trick for me.