A spontaneous gathering of an extended group of friends, usually involving alcohol or some other recreational drug. A sponty is generally organised within a few hours of it starting, so as to not detract from its spontaneity.
A fort or shelter contructed from miscellanious household items, primarily sofa cushions, blankets, chairs. It is used for games and social drinking. The name originates from the first person shooter Weirdies vs. Worm-King, in which Level 8 is based around the protection of a rudimentary shelter, led by King Smointy the Second, against minions of the Worm-King.
The smointy was structurally unsound, yet the snack-eating folk inside were confortable and warm.