DM: 'Huh, really? I guess it sucks to be you then, doesn't it?
DM: SO, let's see... a good monster... no, too weak, too weak...
Me: We could fight a Troll, they're a CR above us.
Friend: Maybe... we do lack a frontline fighter and a healer. Think we have a good shot at winning?
DM: Meh, I just said they were too weak anyways.
DM: He casts Heaven-flame on you.
Me: What's that do?
DM: Kills you.
Me: Right, a lot of spells do. What does it do specifically?
DM: I dunno, throw me those d6 over there. And the D%, eh?
Me:... Okay. *Hands dice* so it really requires luck to survive, but it might do very little.
DM: Actually, I'm multiplying the results, not adding them.
So this is a little off, it's not something the GM says but still, something you don't want to hear in a D&D game.
Iron Kingdoms: A trollkin character in our group had a microtroll familiar that smelled something that even it thought would be disgusting to eat, and he'd be chomping on "munchy men", as he called them. The "munchy men" were the masochistic things that I can't remember what they are called.
Mischevious dwarf gets on top of a coffin in the middle of the dark room, the coffin is surrounded by an eternally burning fire with no visible source. On the top of the sarcophogous is a graven image of a face, screaming in agony. Where the inside of the mouth would be is a hole into the darkness and to whatever is in there.
Most of the other players weren't paying attention to the Dwarf until his player said the infamous words: "Hey guys!"
((Ok, this happened just a few weeks ago)) the party I was with were hunting a medusa in a catacombs under a castle. I was in the front (halfling ranger) and I was spotting at every turn using a hand mirror to look around corners when I came to a door. The door swung inward and I spotted again, rolled for a total of 12 (spot check bonus + 10)
DM: The door opens on a fifty foot chamber, a waterfall trickling into a pool on one side. In the center a learge ornate pedastal with a medusa on top......... ((Yup I'm a lawn ornament now......))