One who does more than his/her fair share of whining and/or complaining, much like that of a toddler in a high chair. A spoon banger--in adult terms--may be a stubborn person who complains about everyday functions.
(noun) A combination of the words 'spoon' and 'poontang'. 'Spoon' representing a sexual position where one partner is held in parallel (also referred to as '66' or '99'), and 'Poontang' meaning the vagina, and more generally, intercourse. Usage is rare, following the same rules as 'poontang', and simply specifies a certain position to be used.