A term that is commonly used by college professors to refer to students that get (by law) 50% more time on tests because of a "learning disability". The disability is typically related to test anxiety.
The term derives its meaning from the fact that disabled students in the public school system often ride to (and from) school in a bus that is about half the length of a typical school bus.
Professor 1: How many short bussers do you have in your class this semester?
Professor 2: I'm not sure, but can you tell me how the fuck those retards get into college at all?
Professor 1: Yeah, fuck the ADA (Americans with Disabilities Act)!