I was once asked to DM for a couple of guys who, through a mutual friend, claimed they could not be outsmarted by any DM anywhere. In the first 10 minutes of the game (a by the numbers dungeon crawl) the wizard had an arm nearly severed trying to retrieve a jewel hilted dagger at the bottom of a sewer grate. After getting some healing laid on him, he tries again... with the same results.
The other guy, playing a thief, never even bothered to check for or disarm the trap. A few minutes later, I describe a block of stone at the base of the wall that looks subtly different than the others. The thief removes the stone, revealing a opening just barely large enough to allow a man to enter, as long as he lay flat on his stomach or back and inch forward at a very slow pace. The light of his torch showed him dozens of red and glittering gems inside the passage.
So, LEAVING his torch outside the opening, he crawls inside. 7 feet inside the passage, he triggers a pressure plate that lowers a metal grate behind him. Unable to retreat, move forward, or fight, he was eaten alive by rats.
Less than one hour into the game, these two guys storm out of the house without a word.