An unexpected hit is a term used to describe a product or work that has achieved unexpected success. In this context, the crossword solutions for the term are WHAM (4 letters), SLEEPER (7 letters), and SUCKERPUNCH (11 letters). WHAM refers to a sudden, powerful impact, while SLEEPER is a term used to describe something that has been overlooked but eventually becomes successful. Finally, SUCKERPUNCH is a metaphor for an unexpected surprise.