This DM had a penchant for placing characters in demeaning situations.
The characters, after fighting through much of the dungeon, found themselves in front of a 100 foot deep pit. Looking into it, they didn't detect anything out of the ordinary. After some debating as to who should go first my monk decides to run down the wall (because he had that ability).
The DM starts laughing and declares that the monk finds himself waist deep in dungeon denizen poop. I got a bit irritated at this point, since the DM hadn't mentioned anything about the scent of poop, and asked how that could be. The DM declared that the scent of all this offal only rose about halfway up the pit and was undetectable from the top. I said, well in that case as soon as I detect the scent I want to make a U turn and run back to the top (as a high level monk with some movement boosting buffs, I had plenty of movement). We argued about it a bit, and finally the DM offered me a high Dex check to pull off the turn around, and I succeeded. My character successfully avoided running into the naughty word pit, but even then the DM basically taunted me about it for the rest of the dungeon.
What I really want to know is who in their right mind poops in a 100 foot deep pit!? You're leaning back, doing your business, lose your balance and fall head first into a deep latrine. Game over. World building at its finest. :/
Like I said, not the first time he pulled that kind of crap, just the most recent that I can recall. Sometimes his gotchas would be of the deadlier variety, like the time he put three adjacent 5'x5' pits in a random spot in a 5' wide hallway of the main thoroughfare of an inhabited dungeon. My character climbed out of the pit only to fall into another. And then again! How the heck did anyone come and go from this darn dungeon!? Then again, I suppose I should just be greatful that those pits didn't double as latrines...