To listen to another persons conversation intrusively and/or clandestinely, to eavesdrop.

AKA keep an ear to the ground. Pay close attention. Ear hustling is being nosy prowling around trying to find something that make sense. "I hate those gossipin' ass choir members up in here - always ear hustling in people's mix and they don't even know the flava of the Koolaid!"

You ear hustle at work, church, weddings, family reunions, and also one other place you will never suspect, the Bible. When you know that Jesus is speaking and what he is saying but it is not to you, that is ear hustling. Ear hustling is not always bad because what is being whispered is always something of importance wrongfully or rightfully.

Then it can be a sign of Narcissistic Personality Disorder (NPD).

NPD is an excessive need for admiration, disregard for others' feelings, an inability to handle any criticism, and a sense of entitlement. Therefore you listen to make sure it is not about you. Sense you have a high disregard for others you will share it once you determine it is not about you. " Girl he didn't pass, he has chlamydia."