I always have a huge spherical central chamber, which everything else is connected to. Said chamber varies in size from fort to fort, but always contains another sphere 3 tiles smaller in every dimension. Said second sphere is supported by supports at the top and bottom (floor on top is supported by a support hanging down from the ceiling above).
At least 8 supports are always used, and each is linked up to a pressure plate in a 6x6 room in one corner of the fort. These pressure plates are trigger able by cats / kittens.
The room consists of alternating doors - walls, with all the doors locked.
A complicated series of pumps and tunnels is set up to fill the secondary sphere with magma, and is then dismantled once this is complete.
Once the fort is up and running nicely and has a population of 60-80 (or when I get bored), I throw a newborn kitten into the pressure plate room.
This way, after a while the kitten / cat will step on the pressure plates in the right order, and all of the supports will deconstruct.
As the pathing of the cat determines when the secondary sphere will explode, It always comes as a nice surprise, especially if the statue garden is located in the central chamber.
I always like to imagine the last conversations of the doomed dwarves;
"So Urist, hows the wife?"
"Oh she's fine, she made a nice gauntlet yesterday"
"Good for her! Hey have you heard about Tekkud?"
"No, why?"
"Well, apparently he started muttering about cave spider si-OHGODITBURNS!"
Urist McSmallTalk has cancelled conversation: Magma
*assorted screaming and burning hilarity*
Urist McSmallTalk has died in the heat.
EDIT: Unrelated to Dwarf Fortress, whenever I make myself a cup of tea / coffee, I always pour out two mugs, So I can have a half-empty one and a half-full one.
It also give me opportunities to use 'me, myself & I' jokes, most of which are tired and old.
Usually something such as
"Why do you have two cups of tea?"
"Well, one's for me, the other is for myself, and I isn't thirsty."