EIGHTBALL
'Eightball' is a highly uncomplimentary slang word standing for a rather objectionable character ('gold brick', 'goof'). The word owes its origin to the billiard game where the number 8 ball has some restrictive associations which make it an object of disapproval. Namely, in a pocket billiard game, popular in the USA, the player loses if he directs the eight ball into the pocket. Hence, the phrase 'be behind the eightball' (in trouble). In the Army the word has likely connections with the expression 'Section 8' which was a section of provisions specifying the reasons for discharge from military service. 'Section 8' defined the reasons for discharge for reasons of mental, psychiatric deficiencies and therefore 'Section 8' figuratively means a 'psycho', a 'moron'.