What have you personally done to your car, just because you either simply didn't know or by accident.
We all did something stupid when we first started and all still make mistakes so fire away,
No judging guys
Some years ago, fresh into playing with cars, I removed my front brake calipers, i installed the left on the right and the right on the left, (because this put the brake bleed niplles upside down) I could not bleed them to save my life and It took me a few days to figure out that I'm a complete monkey
(Head down in shame)