"Happy Singing Peasants": Used by a player to signify that a spot check or perception check roll is a complete and utter failure.
Origin: In a Rolemaster campaign, the party was riding up to the keep of a BBEG. The villagers working the land nearby were oppressed, in that dressed-poorly-miserable-moaning-dirty-and-starving kind of way.
The party's perception rolls (this is Rolemaster) go something like:
Vidor: uhmmm 25?
GM: 25? Really?
Vidor: <sheepishly> I rolled down.
DM: Ok. You see the usual peasants, working the fields if a little unenthusiastically.
Jason: <rolling> Doh! I rolled down too. <pauses> Uhmm. minus 62?
GM: Man. <sideways glance> Ooookay. Happy peasants! The peasants are salt-of-the-earth types, toiling away, working hard and clearly well cared for.
Mark: <rolling> Roll down. No!. 98!!....99!! 65!!! Minus...220 something
GM: <pauses incredulously>
Jason: Happy Singing Peasants!!
"Kick him in": Used by a Player/DM to signify that a contemplated action is a chaotic, horrendously unwise act likely to result in disastrous consequences.
Origin: The player John Maclean-Foreman (now a game designer at Ubisoft) let loose this gem upon our group back-in-the-day. JMF was once playing this good aligned elven Ranger in a Rolemaster campaign. He was bearing a +25 light lean, Holy, intelligent broadsword which could shoot a holy firebolt, three times a day. It was a fearsome weapon in the cause of good.
Cut to the chase: John and the party are in some dungeon/ruin where we've been meeting lots of bad guys. We enter into this room with a great large hole in the floor. An NPC adventurer in armor is on his knees near the edge of this hole, shouting down to someone below:
GM: <shouting down>: "Harry. Harry! Are you ok?"
*ominous growls emanate from the pit*
GM: <shouting down> "Ohmigod. Harry. Are you ok? Move over..."
*a great roaring can be heard from below*
GM: <shouting down, excitedly> "Oh gods!! It's coming Harry! Play dead Harry, play dead!"
At this point the party has walked up behind the adventurer shouting down to Harry
*screams now can be heard from the pit*
JMF: What's he doing. Has he even noticed us?
GM: No, he's on his knees with his back turned to you on the edge of the pit, fumbling with a rope.
JMF: "Kick him in."
GM: <stares incredulously for a moment> Alright. You kick him in.
All other players' heads swivel and look at JMF; everyone is stunned at this.
*more screams from below as he falls then guttaral noises and intense screaming echoes up from the hole*
JMF: <laughing> "He was probably evil..."
GM: <closing his book> So you kill Doric and let Harry die...What's your DB? Nah... never mind - its point blank from surprise.
JMF: <confused> DB, uhmmm from who?
GM: <rolls the dice, in the open> (in Rolemaster, this is A Very Bad Thing)
GM: The light laen sword, realizing you are in fact, a chaotic *psychopath* BLASTS you. 25 and a D class fire. Your leg is in ruins, stunned for 6 rnds, -75, bleeding at 8 per/rnd and you...
That was the end of JMF's ranger, an elf of questionable alignment and even more questionable judgment.
"Nice Day isn't it": Used by a player/DM to note that a player or NPC has just said something during a conversation that is era inappropriate or metagaming that he could not possibly have known and would never have said. By saying "nice day isn't it", the statement is deemed not to have happened and you were instead discussing the weather.
Context:
Player 1: <looking at a sword over the mantle>"A fine sword that is."
GM <as innkeeper>: "Aye I got it back at the Battle of Oerlund. The old king, he gave it to me after the battle. It's elven I think. Glows, and it's still fearsomely sharp."
Player 1: +1 Sword?
GM: +2 actually. "Nice day isn't it?"
Player 1: "Indeed it is m'lord, a fine day."
Origin: I don't know. The core of our gaming circle has been playing with one another for 28 years+ now and I don't remember how this one started. But it's been around since as early as I can remember, late 70's at least.
"You killed it, you keep it": Not so much slang, as a ceremonial phrase. Said by a player to a DM after his character has been slain. For full effect, you are supposed to crumple up the character sheet and throw it at the DM - with sneering contempt.
Origin: A sad but true story. Waaaaay-Back-in-the-day, 26 years ago, the player, Brian Black, was playing this Noldor Elf in a Middle Earth campaign. A fire occurred near Bree and the party had to escape from the burning building. A ridiculously easy saving throw vs. death was forced upon the party members. Every one of them made it - except Brian...
DM: "A 2?? Oooook".
BB: "FUDGE!! FUDGE!!" (well, not exactly fudge, but, you know...)
DM: "Alright...the saving throw indicates you are in some trouble. Make another save vs. paralyzation. Save or die."
<Brian rolls as everyone gets up and rubber necks to watch this die roll. BB had a legendary reputation for outrageously fudging die rolls. But this time, 7 other players were there to witness it.>
*1*
DM: "oooh".
*silence fills the room*
DM:"Uhmm. You're dead."
BB: <ranting and raving now> "FUDGE, FUDGE. FUDGE!!!!!"
* BB balls up character sheets, whips it at DM's head* "You killed it. YOU KEEP IT!
Ever since that time, capricious death at the hands of the DM must be met with this ceremonial sneering declaration.