Well, not as dumb as this truck, but pretty dumb. I did a quick 5,000 mile service on my ‘91 Corolla: oil change, tire rotation, brake inspection. Almost finished, starting to rain, and I started the engine whilst I ran around snugging the lugnuts. When I got back to the front, I discovered that I’d left the filler cap off and I’d showered the underhood area — and the driveway in front of the car — with fresh motor oil. Probably the better part of half a quart. Lovely. I ignored the environmental disaster sign at the car wash and pressure washed the affected regions with soapy water, which helped a lot, but DUMB! Never done that before and I’ve probably done 100 oil changes in my lifetime.