Umapati Swami : Today, in the entranceway to Prabhupada's quarters in Vrindavan, there's a store but that used to be a vestibule where Prabhupada's secretary, Harikesa Maharaj, would sit and type. Once I was talking to him there when Palika came. Harikesa told her, "Palika, tell me everything that's going on in Vrindavan." She told him everything that shouldn't be going on and left. Then Harikesa peeked through the door to Prabhupada's quarters and saw Prabhupada walking away. He said, "Oh, no, Prabhupada heard everything."
The next day in his class Prabhupada said, "If you have illicit sex in Vrindavan, you will take birth as a Vrindavan monkey. That is Krishna's mercy because you have taken shelter of Vrindavan. But stop this monkey business."
Reference:Memories Anecdotes of a Modern Day Saint - Volume 3 by Siddhanta Dasa