(Sri Caitanya Mahaprabhu)
Prabhupāda: So Caitanya Mahāprabhu's special feature, as you see in the picture, He would simply raise His hands and ask anybody to chant Hare Kṛṣṇa, Hare Kṛṣṇa. And people will, in the crowd, they will also respond to Lord Caitanya. So in this way, at Benares He was enjoying.
bāhu tuli' prabhu bale—bala hari hari
hari-dhvāṇī kare loka svarga-martya bhari'
(CC Adi 7.159)
(Whenever the crowds were too great, Śrī Caitanya Mahāprabhu stood up, raised His hands and chanted, "Hari! Hari!" to which all the people responded, filling both the land and sky with the vibration.)
And the sound of "Hare Kṛṣṇa, Hari bol," that become... According... There are two slogans. One Hare Kṛṣṇa, Hare Kṛṣṇa. And another, short, is Hari bol, Hari bol. You can practice also that. Hari bol.
Devotee: Hari bol.
Prabhupāda: Yes. Hari bol. That is a shortcut of Hare Kṛṣṇa. Yes. Hari bol. Hari bol means "the sound of Hari, or the Lord." Hari bol. So whenever there was some greeting, Caitanya Mahāprabhu used to answer, raising His hands, "Hari bol."
(Srila Prabhupada Lecture, San Francisco, March 18, 1967)