gack

My current exclamation of choice. It's particularly apt when pointing out something small that has gone awry which could potentially contribute to a chain of events that will cascade into something huge going supernova (the banana peel on the stairway routine, see also: Rube Goldberg).

Also good for pointing out things so terribly, awfully, soul-crushingly bad that a sort of cute noise is needed to break the tension (the VP of Sales resignation followed by a short order of COO resignation with some CIO resignation on the side - an example taken from my recent history. Yes, I said gack!).

According to cow of #e, gack is also the thick, grey, slimy smelly stuff that builds up in layers and clumps ("thick, juicy clumps", even, in her words) in musical instruments, particularly brass ones. Apparently it's good to clean your instruments often and thoroughly...

Nickelodeon also once marketed a slime-like product under the name of Gak(tm), though I don't know if that has anything to do with cow's choice of nomenclature.

gack or gakk

verbiage/slang term among LARPers (generally those of the Camarilla variety) for having a character killed; generally in a severely brutal manner.

"You hear about that Tremere Archon?  He gakked that Birmingham rogue last week and mailed his remains to the dude's sire."

Not necessarily certain of the genesis of the word, but I'd wager it has its origins in onomatopoeia: sounds vaguely akin to a death rattle.