Literally "Shout Hari!", it is not unlike the phrase "Praise the Lord" and is used in the same way, since Hari is one of the names of Krsna.
Haribol! and pass the potatoes.
In religious festivals of Gaudiya Vaishnavism Hari Bol is called out meaning: "Sing the name of Hari" or "Call out (or chant) the name of Hari". (Hari being the name for Krsna and Visnu)
From a more direct hindi translation: Bol = to speak, Hari = (a) god
It is used in many Hindi devotional songs.
Radha Ramana Hari Bol
A classical example of overgeneric Hare Krishna jargon. The equivalent of "Hey", "Hello", "Have a nice day", "Good night",etc. Bears a semblance to the way the Smurfs use the noun "smurf" and the verb "smurfing", though not as widely applicable.
Haribol Ma'am, I'd like to sell you a book. No? OK, thanks anyway and haribol!
A common misspelling of the name of a source of happiness for both young and old alike. Although widely used it is suggested that refined sugar products can in fact be carcinogenic in nature. Avoid.
Happiness is Haribol...