The term 'shell game need' is a reference to the classic con game of the same name. In this game, a PEA or other small object is hidden under one of three shells and the player must guess which shell it is under. The crossword solutions for this term are 'PEA' (3 letters) and 'PEAS' (4 letters). The word 'PEA' refers to the small object used in the game, while the word 'PEAS' is a plural form of the same word.