E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Sharp.
Sharp’s the word. Look out, keep your eyes open and your wits about you. When a shopman suspects a customer, he will ask aloud of a brother-shopman if “Mr. Sharp is come in;” and if his suspicion is confirmed, will receive for answer, “No, but he is expected back immediately.” (Hotten.)
