A lot of carnival rides. A lot of them have long-ignored mechanical problems, and the people operating them aren't exactly rocket scientists.

Pushing someone in the water as a prank. Why is that still a thing? I've heard of people getting seriously hurt or drowning. Even a redditor said that they knew how to swim but they were taken by surprise so their body froze up.

Letting small children play with dogs. Especially medium to larger breeds that can do a lot of damage. And yes, I’m looking at you: pit bulls, akitas, German shepherds, etc.

Even that special angel of a dog who has never shown aggression before, can react when feeling stressed.

I will fight anyone and die on this hill!!

Edit: I know not everyone thinks this but there’s a lot of folks out there who will deny that their precious dog COULD EVER do harm. And that is plain false.

Not doing the dishes and mum coming home.

Crossing the road, even when doing it "properly".

Water that you only *think* is deep.
Always check before you jump. Always.

Wet tile.

Re-ligion.

Alcohol.

Retail: It should go without saying, but you're way more likely to get what you want when you're friendly or at least respectful toward the person working.

I work at a casino, the cheat code is: don't gamble.

One of my exes told me that ducks can't fly. When I said that was absurd, that in fact the ones where we lived migrate hundreds or thousands of miles southward every winter, she said that they do that by walking. My mind was blown, but I protested a little harder, and she then called her brother to put him on the line who also defended her assertion that ducks can't fly, they walk south every year to avoid the winter.

I felt bad for them not just because they lacked this basic knowledge about the world, but also because clearly neither of them ever played Duck Hunt on NES.

Anytime since when I am outnumbered in an argument where I’m confident that I'm right, I remind myself that no matter how many people think ducks can't fly, they can.