Well I myself have not done anything too stupid as yet but my BF has . He did the exact same thing that Scooter79 did , 5 litres of oil over the garage floor. I had to race down to the beach and grab a few buckets of sand to help clean it up. Worst bit is it was his 300zx , most painful car ever to do anything on.
He was also adjusting the idle speed on the carby of his XY and shoved his elbow in the blade of the fan , didnt really phase him though, has a good scar from it too.
And last but not least he was playin with a VW one day , not sure what he was doin but he managed to get some metal off the car stuck in his hand. It's still there .. the car was blue by the looks of it. LOL