A derogatory term used as a form of retarded yet somewhat more retarded than usual. Word derived from the show "Bobobo-bo Bo-bobo" which was a show on cartoon network. If you look at the wiki on bo AKA (Bobobo-bo Bo-bobo) you will most likely see why this term is used.

(adjective) Showing phenomenally poor qualities; especially intelligence, taste, or character; lacking any redeeming features whatsoever.