In late `97/early `98, I was working as a manager at a BK, in between radio gigs. On Friday, January 2nd they were rolling out a new french fry - they called it "Free Fry Day". My boss says "Before you leave tonight, we need to have all of those fry vats emptied, cleaned, & refilled with fresh grease for tomorrow." Being that it was New Year's Day, & Michigan was playing for a national championship, I was the only non-teenager working - so I had to do all of the work myself.
I got it all done - save the last big block of shortening, which had to only be put into the fryer & we could all go home. I had a teenager open the box, dump it in the vat. He neglected to check it first - There was a piece of the cardboard box stuck in the shortening - which then caught all 3 vats on fire. & you could put it out by putting the tops on, because the shortening was sticking up out of the vat. So I had to get the fire extinguisher out - put it all out - drain them all again ... & then do it myself.