In this context, "gross" is likely used as slang to mean something cool, incredible, or impressive. "Gnarly" can also be a slang term used to describe something that is impressive, extreme, or amazing, often referring to something that is visually or audibly striking.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: "Gnarly!". Explanations are generated by AI and may be inaccurate.