Eye, slangily

PEEPER

Think of what you might call one of your eyes when joking about someone watching you too closely.

"Eye, slangily" is a casual way to refer to the human eye, and "peeper" is a well-known slang term for it. The clue plays on informal language, where "peeper" has been used in English since the early 1900s to mean an eye—think of phrases like "keep your peepers open." It’s a straightforward slang reference without hidden wordplay, just a fun, everyday alternative to the standard word.