Lets hear everyone's best and worst GM encounter.
Heres mine:
Best = I was a part of a GM event in Castle Mistmoore where the GM actually took on the form of Mayong Mistmoore. He whooped up on everyone that came in the castle. Every time we'd die, we'd recruit more and more people from the surrounding zones. I don't know if he ever died, but was a super experience!
Worst = I fell under the zone of Dawnshroud peaks. I was about 100 feet under the zone. It was like it was a whole different zone underneath. I could see the terrain, mobs, and PCs walking above me, but there was no way I could get out. Took 6 hours for a GM to respond to my petition. All he had to do was summon me to above ground.