Almost ate mushrooms my partner who was new to mushrooming had picked without checking them myself. But I did check and they were one of those that look a lot like a very good edible mushroom, but will kill you.
F'd around and found out on the sea ice as a kid. Thankfully wasn't alone.
Also have one of those near death lifting experiences. This was a loaded hack squat that someone has secured poorly that fell on the floor right as I walked past it. The super sharp edge went right past my head.
One morning almost late for work in a shitty old Golf and low road visibility I decided that passing a long truck is a good idea. Out of the rain & fog came another car, all three of us just fitted on the road and nobody died. Never drove like that again.
In my village we used to do this thing as teens when someone with a moped (always tuned way past what it should go) would push others on a bicycle. One day we decided to do this in a way where one is pushed by the foot of the moped driver and other hangs in the back on their shoulder. Of course we fell. I almost landed in a way that would have snapped my neck, didn't walk normally for days I was so sore and my moms bike came home in the shape of an S.
Also did a lot of stupid dare stuff as a kid. Probably was close to death far more often than I realize.
These days I am overly cautious.