True story. My mother in law had passed away and we were getting her house ready to sell. A phone call comes in to the house. From "the IRS". They asked if my mother in law was available. I said "not at this time, can I take a message?" Dire warnings and threats of police action were uttered. Threats of lawyers. Yada yada. All definitely not true.
By the way, I could hear the call center noise in the background the whole time.