Meaning retard, derives from the name of a 'short bus' company called Nebard's. Calling someone a nebard suggests one rides said buses and is therefore a complete fucking retard (as short buses are the common method of transport to and from school/college for mentally disabled students).
To be a retard - act retarded or stupid - yes it is taken from a bus company - this company is located in wakefield and me and my friends (people may contest this) were prob the first people to start using the name nebard back in early 2000.
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.