Originally Posted by VariaVespasa
Thats a Terry Pratchett Discworld thing originally (or at least predating oots)- Million to one shots crop up nine times in ten.
For the old West End Games Star Wars roleplaying game, there was a Rebel Special Ops book that included a glossary of amusing spec-ops slang. There were various sarcastic names for missions of increasing difficulty, culminating in the mission where the odds of survival were one in a million. It's name was the "Skywalker Special".