Later that week, the guys wanted to change the oil on the MT St Helen's van. Named because, being an old utility van, had a billion miles on it, and a leaky exhaust manifold that leaked into the cab, so we drove it with windows open. In winter.
So they borrowed my tools, I told them what to do, off we go to the store to let them work on it.
On the way back from the store, we see the Mt St Helens van on the side of the road, hood up. Oh crap. Pull in behind them, "Hey, what's wrong????" The guys come around from the front of the van...
COVERED IN OIL... 

..
The van's owner nearly in tears, OMG, I broke it, it was shooting oil all over the van! (they left the engine cover off to take it for test drive...) Turns out the old gasket stuck to the engine instead of coming off with the old filter, new filter went on, so they had 2 gaskets. The first gasket is held in place by grooves on the filter. The orignal gasket is held in place by pressure of the oil filter screwed on.... which isn't enough to hold it in place, so the 2nd gasket slipped, and the oil shot out the hole.... all over the van, all over the owner's brand new winter coat... oops..
Popped the filter off, threw away the extra gasket, put the filter back on, started it up, and all was fine...

except that new coat...
Randy