1) Conceitedly immature 
bombastic
• (a.) Alt. of Sophomorical
self-assured though immature affected bombastic overblown 
sophomoric, sophomorically 1. Of or characteristic of a sophomore or sophomores. 2. Exhibiting great immaturity and lack of judgment: such as, 'sophomoric behavior'. 3. Suggestive of or resembling the traditional sophomore; intellectually pretentious, overconfident, conceited, etc., but immature: 'He often asks sophomoric questions.' ...