Bill was an avid Rolemaster player who really felt the need to prove the competency of his new Healer character. The rest of the players met this character in the middle of an adventure: they found him locked in a prison cell.
Bill: "You need me to join your group. I'm a Healer, and I'm so good that I can regenerate from severe wounds! Go ahead, hurt me and I'll show you."
Not often invited to hurt fellow PCs, the players happily obliged... stabbing him through the bars. Bill contentedly demonstrated his character's ability to automatically heal damage.
Bill: "I can even regenerate from mortal wounds! Go ahead and try to kill me."
Again, the group obliged with enthusiasm, stabbing the Healer repeatedly until he stopped breathing. Moments later, the character was healed and standing once again.
Bill: "...and I can do it more than once per day!"
Jumping the gun a little this time, the players lept into furious action. They stabbed the Healer until he fell, cut off his head, poured a flask of oil over him, and lit him on fire.
Bill and the rest of the players sat around waiting for me to describe the Healer's miracuolous recouvery.
DM: "Actually Bill, you can't recouver from that... you can theoretically resurrect more than once a day, but you've already used all your power points with your previous demonstrations."
They really could have used a Healer on the remainder of that adventure...
One character collected the Healer's ashes, and put them in a jar. For awhile we discussed the feasability of the Paladin hand-grenade: the cremated remains of a Paladin poised to resurrect himself as soon as the jar was smashed (by throwing it at your foe).
Of course, I've been known to do a few stupid things as well. One of my favourite rogue characters, Kayli, was voluntarily lowered by the rest of the party down a really long shaft so she could fetch a book in the room below without stepping on the floor. The book was a lab diary, fiercely guarded by an elemental who attacked anyone that stepped on the room's floor. The room itself was a scrying chamber; a magically moist clay tablet lay directly below the shaft where shadows from a complicated magical mechanism suspended far above could be traced onto the large tablet's surface. The augeries were later transcribed by the Mage into the lab diary.
So here's Kayli, very smug in the knowledge that she's beat the dungeon without endangering the group. She tells the group to pull her up quickly if she tugs on the line once, and start/stop lowering her if she tugs twice in quick succession. Slowly they lower Kayli until they can no longer see her. Near the bottom, she tugs the line twice, and the party stops lowering her.
With a little acrobatics and a lot of stretching, Kayli is able to grab the book from its pedestal. The moment she touches it though, the elemental rises from the floor and prepares to attack. Caught up in the events, and panicking almost as much as my character, I physically pantomimed tugging on the rope... twice.
The party happily obliged by dropping me face first into the tablet of wet clay.
When the party hauled me out of there, I explained how my muddy appearance was the result of the elemental's attack.
In a later adventure, our party returned to the dungeon and had to take a more mundane route down into the scrying chamber in order to accomplish a disenchantment of the keep. After we fought and destroyed the elemental in a particularily harrowing fight, my character limped ahead of the group so she could beat them to the clay tablet and erase the evidence of her embarassing mistake.
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