Back in 40d, in my first fortress ever that I actually knew what I was doing (Read: figured out how to dig) I had actually gotten pretty far. To around 150 people if I remember correctly.
They lived under horrible conditions, but were all happy somehow. I mean ecstatic. I didn't pay much attention to that, but one day that changed. After my 3-5th goblin invasion ever, I actually couldn't keep them out. They got inside and chaos was everywhere. Many good dwarves were injured and killed. I had my first tantrum spirals. About 40 of my dwarves were gone, leaving me with a grand total of 110, of which atleast 25 were injured. I then got bored with the micro-managing to send dwarves back to work and re-assign everything. So, like anyone else would do, I dug out a 7x7 room deep underground in true airlock fashion connecting to my magma pipe. I put a pressure plate a z-level down underneath a metal grate connected to the exit door (the one not near the magma) and ordered every single one of my dwarves to go there. Every single one of the 85 able bodied dwarves showed up as planned, except for my best soldier who survived the goblins and was ordered to pull the trigger and release the lava the next time a goblin invasion happened.
In due time, my dwarves inside the panic room were getting angsty and starving. Then luck came as goblins charged (Read:walked) into my bedrooms (Where the injured dwarves were still resting) and started slaughtering them all. Tantrums began happening left and right inside the panic room. Dwarves went insane, dwarves went berserk. Then the goblins mopped up the injured dwarves, and the trigger was pulled. The lava flowed in and began burning all of the dwarve's ankles, until falling on the pressure plate and releasing them. Flaming dwarves left and right charges, going berserk and all and spreading the fires. The goblins wanted in on this, so they started attacking them too. There were no survivors.
tl;dr I turned my first functioning fort into a dwarf fire-bomb.