SPOILERS (Sunless Citadel)
My favorite "Critical Hit" started out innocuously... but quickly became legendary in the group I was in.
We were running through the Sunless Citadel. I was playing a dwarven bard with a fixation on alchemy.
SPOILER ALERT!!!
Our party ran into one of the goblin barricades... the ones with caltrops scattered betwixt the party and the barricade. The goblins started pelting our party with missiles. The rest of the party was without missile weapons, and so they started slowly and carefully navigating the hallway amidst the hail of missile fire. Annoyed, my first reaction was to pull the last flask of alchemist's fire from my belt pouch and hurl it at the goblins. The "to hit" roll was a little low, and the flask broke against the (wooden) barricade, burning down and, while not causing the barricade to go up in a conflagration of smoke, did start a slow, smoldering burn on the side closest to us.
I tried to use a flask of oil to "fan the flames" at the barricade. I rolled... a natural one. The oil flask dropped from my hand and shattered on the floor.
While the rest of the party gingerly made their way down the corridor, I examined my character sheet. On my next turn, I promptly announced that I was cutting my bedroll from my pack. While the DM and the other players stared at me incredulously, I informed the DM that I was going to start rolling the bedroll along the floor ahead of me as a "caltrops sweeper" - the caltrops would embed themselves in the bedroll and I wouldn't have to worry about stepping on them.
Two rounds later, after I had "swept up" several feet of caltrops, the DM rolled a "to hit" roll on the bedroll - rolled a natural 20 - informed me that one of the caltrops had managed to cut the tie that bound my bedroll up. He also joked at me that my bedroll was now soaked in oil (from the flask I had dropped on the floor). The rest of the party enjoyed a good laugh at my expense.
When my next turn came, I said, "I'm throwing the bedroll over the barricade."
DM: "What?"
Me: "Well, the bedroll is soaked in oil and it has caltrops and broken glass embedded in it and it's not rolled up any more - so it's no more good to me as a bedroll. I'm going to try to hurl it over the barricade, caltrops-side down, and just low enough so the "bottom" of the roll as I throw it lands on the still-burning barricade, while the rest of it "Swings over" the barricade to impale the goblins with caltrops. Oh, and since the barricade is still burning, I'll hope it catches fire, too, due to its being soaked in oil."
DM: "Did you take Exotic Weapon Proficiency - Flying Bedrolls?"
Me: "Nah, but that's okay, I'm having fun."
DM: "Okay, make a hit roll."
*I rolled a Natural 20.*
DM (jaw drops): "Um... roll to see if you confirm the critical threat."
*I roll a second Natural 20.*
DM: "Wow. Um. You fling the bedroll through the air and it lands just as you said, impaling and then burning the goblins beneath it. *a couple of die rolls* It then bursts into flames. *a couple more rolls* After a few seconds of shrieking, all is silent."
Me: "Excellent. I take the
Flaming Flying Spiked Bedroll of Death and try to put it out." (By now, the rest of the party is laughing at my clever use of a "bad situation" to make a fun ending).
DM: "Okay, it's barely salvageable - it will never make a good bedroll now, you know... and there are two goblins "stuck" to it thanks to the caltrops and there's glass all through it."
Me: "That's okay. I take out some rope and tie it like a banner to my ten-foot pole - I'll chop a foot or two off the end of the pole and lash it together if I need to... basically, I'll make a banner pole in the shape of a "t" then tie the corners of the bedroll to make it stay unfurled. I'll parade it around in front of us as we march through the rest of this dank hole..." *uproarious laughter from all, including the DM*
Ever since then, my dwarf was known for the "Flaming Flying Spiked Bedroll of Death" (it helped that, being a bard, he was constantly singing about it, too).
--The Sigil