My wife caught on. Once upon a time I told her I bought a new gun. She must have been in a sour mood that day, as she replied "What are you telling me for?". So I took that to mean that I no longer needed to inform her from that point forward.
All was well for a long time as she mostly can't tell one from the other. I have a good variety of configurations as far as style, barrel length, finish, etc.. Then I messed up. I bought a 1911. She spotted it as "different".
She asked why I didn't tell her, and I relayed the above experience back to her which she did not remember. Of course then it was "O.K. how many guns do you have?". So now she keeps count. *sigh*.