What does "pas de vente" mean?

I watch a lot of British programing and now and then I hear a character say this expression “pas de vente”. Not sure if the spelling is correct and I assume it’s colloquial. It’s always said when a servant or waiter is nearby and one of the parties to the conversation doesn’t want them to overhear what is said. I’ve searched high and low but just can’t seem to find out what this means.