Really? I didn't realize it had anything to do with that. I thought it was simply about how the "short bus" looks like a normal bus from one angle, but disproportionately small from another. As in, DPRK threats look scary but really don't have much backing.
It refers to a smaller bus used to ferry students to special education programs, with the implication that they're all dumb and so is the person being insulted.
That's really not how it's used around here (west coast canada). They aren't associated with special needs kids. When I rode motorcycles at university the term was used for any silly-looking vehicle. A Jeep TJ with a lift and big rims, or a large truck with a tiny trailer would be called "short bus" if it looked taller than long.
I think that was the context Archer meant. (s04e09 "The Honeymooners" when Lana an Archer pose as newlyweds)
