There was a revolt in my fortress that wiped out 30 dwarves and injured 15. It started simple.
The queen's consort had a demand, and like all his demands, it was subdued. I had no idea there was a demand until I saw the captain of the guard accost a military dwarf who was sparing. The jails were closed for renovation, forbidden due to a nearby magma/water/obsidian project... so the uppity guard thought he'd just give some random dwarf a beating. We'll he picked the wrong dwarf. His unarmed blows concussed the miltiary dwarf, through is steel helm no less... and he ended up dieing. His squadmates weren't having any of that and jumped the captain of the guard. The other guardsmen nearby jumped in to help the captain. Then other military squads jumped in. Then family members. Weavers were beating up brewers, cats were fighting dogs. I had no idea what to do. By the time it finally died down I had lost half my military, a bunch of craftsmen, and all of my nobles except the queen and her consort. That god damn consort... examining his thoughts and preferences showed he didn't give a damn. So I set him up for a magma swimming lesson. His parting statement "Bah, changed my mind!" Too late for that.
So... everyone was covered in dwarven blood, and spitting in each others faces, but no more fights have broken out. I figured it was time to make a waterfall/bath to cool everyone off. A good reason to figure out how pressure plates work. I built a 3x3 reservoir, with each corner channeled, over a 5x5 room, with statues under the channel spots. With both retracting and raising bridges controlling the flow into and out of the 3x3, I made a serene little shower/bath/waterfall. Its been about 6 months and the blood is still washing off...
Anyways... it was a crazy experience I was totally unprepared for. I love DF.