A phrase used to perplex, confuse, and annoy a person who really wants to talk to you. It can also be used to reroute the conversation in a direction more suiting to your interests by making the other person forget the original topic.
When you're making a phone call in New York City, this phrase usually means that the person on the other line isn't putting you on hold to help you, but to either talk to another customer or to make a personal call.