Come on folks confess your worst ever mechanical mistake and embarrass yersel in public. You can even pretend it was your mate and not you.
When i was 18 i had a Suzuki GT380 which handled worse than me after 10 pints of stella.
As the front end was particularly bad i thought i'd replace the fork oil with something thicker to stop it bouncing around quite so much.
So i put the bike on the centrestand and unscewed the first fork cap. I then unscrewed the 2nd fork cap.......BOING.......
Fork cap shoots off like a bullet and richochets all over the garage.
As i didn't have the brains to put a support under the bike, the front end of the bike collapsed, the fork springs shot out as well, followed by 2 streams of dirty fork oil all over the place.
What a feckin' mess.
The story doesn't quite end there. When i i put everything back together i wanted thicker oil in the forks rather than the de rigeur ATF or fork oil (no special weight fork oils back then) i used 2 stroke oil which was about 30w instead of the fork oil or ATF which was about 10w i think. At least i wouldn't have to worry about de-coking the forks.
It still doesn't end there, as i still wasn't happy with the handling i tried EP90 gear box oil to stiffen things up even further. Well at least i was young and trying, very trying. No wonder Nelly makes me stand in the corner on my own when i go there

Moral of the story, either learn to do it properly, workshop manuals are good things, or get the experts to do it.