Phalluses, mefinks.
As for me, I'm really lazy with bedrooms. My dwarves sleep four to a room (3X3, smoothed and engraved, but still). They're like tiny, alcoholic, sociopathic Chinese people.
My nobles always get metal furniture because I like to think it hurts their arse.
I walled off the edges of a cavern once. Way too much hassle in the end...and undwarfy, so I'm not doing it again.
I quite often make it a point to drown/impale/otherwise execute useless migrants. Like those guys who only have "Novice Fish Dissector". Sometimes I turn one of them into a doctor...the others are bundled into a millitary squad and told to go stand in the spike room. More often than not, this leaves some orphans in my fort. Seriously, Urist McKiddo moved to my fort with his family, wondering what sort of adventures he'll go on. First thing he knows, mommy and daddy are skewered on metal spikes, and he's told he now lives in a room with three other big, sweaty dwarves that he's never met before. He lies awake at night, crying about how cruel life is, only to get a sock thrown at his head and told to shut up because Urist McMiner wants to sleep.
Corpses of invaders are left outside. Only limbs, teeth, horns and ivory (from trolls) are taken inside...to be turned into bolts and worthless crafts to sell to the elves. All this because making refuse stockpiles is too much of a habit.
I once left a minotaur sitting outside in a cage for five years because I was too much of a pussy to deal with it.
I'm too lazy to go to war with the elves.
And last but not least...I only sell crafts and cut gems.
Yeah...forgive me, forum, for I have sinned.