I first heard that on the Hak5 podcast, and assumed it was a Virginia think (Darren's from Virginia), but later he realized that no one else said it that way and it took a while for him to remember where he'd learned that. I think he got it from his friend "mubix" (Rob Fuller) who is a US Marine and apparently the Marines call it a "tack". Not sure if it's true or if mubix just invented that, but it's my best guess :)
I also call it a "tac". The habit comes from my time in the Navy, where it comes from the naming conventions for compartments (rooms) on a ship. Marines probably call it that for the same reasons, as many of them end up being on a ship at some point (and they're part of the Department of the Navy, so they share a lot of tradition with sailors).
e.g. "3-74-4-E" would be pronounced "three tac seventy-four tac four tac echo" (3rd deck, 74th frame aft of the bow, 2nd compartment outboard of the centerline on the port side, and it's an engineering space)
I've also avoided calling it a "dash" since I left the Navy, since dashes and hyphens are different characters in typography.
