Sit

The #sit extended command makes your character to sit down; this can have different effects (and messages) depending on what you're sitting on.

Sitting on a trap while you're trapped in it abuses wisdom, and for some traps, makes you stuck in it longer, pool will rust your armor. Probably the most used feature is sitting on a throne. Siting on an altar lowers your luck

You can also lay eggs by sitting if you've polymorphed into a female oviparous monster.

Tactics

If you are needing an emergency escape method such as a teleportation trap or a trap door, and you managed to escape it when you entered the square, you can just #sit to activate the trap.

Currently there is a bug associated with this. For example, a gnome dies in a pit and you want to loot the gnome, but you escape when you try to enter the pit. Trying to #sit gives you a message about the gnome corpse being uncomfortable to sit on and you won't fall in the pit.