A prig might lecture his friends about their manners, or complain about having to eat at a diner instead of a fancier restaurant. Prigs tend to be self-centered and uptight and aren't much fun to be around. In the eighteenth century, prig meant "precise in speech in manners," and implied someone who was deeply religious. The origin of the word is a mystery — its earlier meanings included "dandy or fop" and "thief."