What Is Your Most Embarrassing Technical Story?

Automobiles are machines, and working with machines sometimes means getting technical, at least technically. What is your most embarrassing technical moment, with cars or other machines?

Mine involved a simple oil change at a friend's house. That car used the common metal-can oil filter, but I forgot my oil filter wrench, and my friend didn't have one. So I use a large channel-lock style wrench and twist on the new filter. Start up the car, drive it outside, immediately find a sea of new motor oil that had just been inside my engine. I later found a new oil filter with holes from the wrench mounted on my car. It felt bad.

Photo Credit: The United States' Library of Congress, via Wikimedia Commons.