that would be telling

that would be telling

That would give away the secret or surprise. A: "Does this mean that we're getting a puppy after all?" B: "Now, now, that would be telling. Just have patience!"
See also: telling, that

that would be telling

that would be divulging confidential information. informal
2000 Imogen Edwards-Jones My Canapé Hell ‘Are you propositioning me?’ I say, attempting to look provocative in my Devonshire home-knit and Angora Dutch cap. ‘Now that would be telling,’ he smiles.
See also: telling, that