I have to bring up the Murphy's Rules:
"In a 30-minute RuneQuest battle (Chaosium) involving 6000 armored,
experienced warriors using Great Axes, more than 150 men will decapitate
themselves and another 600 will chop off their own arms or legs..."
Butt let's see...
The Champions referee who proudly told me "So I looked at the player's character sheet, and I saw he had "Hunted by Mechanon" as a disadvantage. So I think to myself, "Hey, Mechanon is an evil robot that doesn't care anything about humanity. So he just nukes the city and kills the guy. Five minute game, dude!"
And then there was the D&D DM who redid the encounter table to be TRULY random- everything had an equal chance of being encountered. There was an qual chance of meeting 1D20 orcs as there was an elder dragon. Which is why, as soon as the 1st. level party started walking down the road, *rollrolllroll" "You meet a lich. Roll for initiative." ONe round later, "Yo're all dead. Make new characters."
But the worst?
A friend mentioned the first time she gamed, with the first guy mentioned above as DM. The scenario boiled down to in the first five minutes, "Your elf is caught and raped by a hundred orcs. ..what? You failed your Hide in Cover roll!"