So I figure since we are trashing other GM horror stories I should give one or two from my own meager GMing experience.
So it was after my first adventure in AD&D I must have been like 10 at the time and my dad was the GM, but as a 10 year old clearly I thought, well I could totally be a GM, then I could make epic battles and crazy annoying wizards that are so damn hard to kill even against a party of 9… Like our arch-nemeis Leptor, who could kick our asses with an invisible imp and pit traps, we hated him a lot. Turned one of his generals into a tuna, good times.
Eventually I tried again with GMing when I was a bit older, and it was going pretty well had a dwarf fighter and drow rogue doing quests etc. until I got to an adventuring module where you basically get kidnapped into a spaceship or something and these aliens have tech weapons that can ignore armor. Well my players were not really too happy with the fact that they lost their equipment and that the module creatures were basically ignoring their armor, although they did enjoy the fact that the creatures cores were basically usable as grenades. So I ended up giving the reigns of that campaign back to my Dad, and joined in with a necromancer who I had intended to be the BBEG of my campaign, and since my dad said that this was the last campaign he would GM for us since I kept taking over and giving it back to him we stuck with it and it was good fun, but I still had a reluctance to GM until this previous year.