I've had a few "ut oh" moments in the shop and they have been eye openers for sure.
My closet call ironically came when trying to get a 5 hp briggs engine on a tiller to start. It had flooded and I used a 1 gallon plastic pail to drain the gas from the carb into while I fixed the needle and seat. It still wouldn't start so I pulled the spark plug and checked it for spark by pulling the starter cord. Gas blew out the plug hole, hit the spark on the plug and ignited setting the gas in the pail on the floor ablaze almost instantly.
Thankfully I knew right where my hand held extinguisher was and got to it without even thinking and got the blaze out quickly before it could spread to other flammable stuff close by. I now keep WAY more handhelds all around the shop...just in case.
Someone mentioned 4 post lifts above...I'll also add that I was always much more concerned about a car or truck falling on me with my two post than I am now working on my 4 post. Just have to make sure if the car falls you aren't in between the car and the ramp is all.