When I was a kid my neighbor raised his hood on his '65 Ford Galaxy and I ran out to see what he was doing. He said that his tranny was slipping and he had determined that the ATF was low. I stopped him just as he was about to pour a quart of ATF into the engine! He explained, "It goes in the engine and then back to the transmission." I explained reality and he started thanking me over and over. He ended-up getting a lot of miles from that car.
I was changing the oil in my girlfriend's '79 Malibu V8 (now my wife of 21 years), I had it on ramps and she was helping. I was explaining in great detail how to remove the oil filter as I unspun it. Just as I was getting to the part about it being full of oil so you have to be careful not to spill it, it came off before I was ready, it spilled HOT oil on the sides, I lost control of it and it went rolling off under the car with oil spilling all over! Fortunately, I had newspaper covering most of the affected area, but this was indeed embarassing. Fortunately, she didn't laugh at the time, but it makes a good story now!
After having changed oil in various cars of mine for at least 15 years, I thought I had it figured out - I was Mr. Efficiency. One time I started thinking about something else as I was finishing-up and accidently stepped into the oil collection pan with my tennis shoe! I had moved it out from under the car, there was plently of room around it, and I stepped right in the center of it! Fortunately, I was wearing old socks and shoes, so the loss was minimal. I wish I had a video of myself doing that.