An extreme moron. This term was not coined by Bugs Bunny, who only used the term maroon, and then only once. Ultramaroon was a favorite term of "The Champ", a longtime Canadian syndicated radio feature.
"The ultramaroon goes for the head fake. Uppercut, straight right, and a flurry to the solar plexus. 'How's that?" -The Champ
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.
"Base we've got some square groupers floating outside of Miami harbor."